| 1 | ---
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| 2 | title: Builtin Commands (Oils Reference)
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| 3 | all_docs_url: ..
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| 4 | body_css_class: width40
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| 5 | default_highlighter: oils-sh
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| 6 | preserve_anchor_case: yes
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| 7 | ---
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| 8 |
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| 9 | <div class="doc-ref-header">
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| 10 |
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| 11 | [Oils Reference](index.html) — Chapter **Builtin Commands**
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| 12 |
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| 13 | </div>
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| 14 |
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| 15 | This chapter in the [Oils Reference](index.html) describes builtin commands for OSH and YSH.
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| 16 |
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| 17 | <span class="in-progress">(in progress)</span>
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| 18 |
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| 19 | <div id="dense-toc">
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| 20 | </div>
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| 21 |
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| 22 | ## Memory
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| 23 |
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| 24 | ### cmd/append
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| 25 |
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| 26 | Append word arguments to a list:
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| 27 |
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| 28 | var mylist = :| hello |
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| 29 |
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| 30 | append *.py (mylist) # append all Python files
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| 31 |
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| 32 | var myflags = []
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| 33 | append -- -c 'echo hi' (myflags) # -- to avoid ambiguity
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| 34 |
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| 35 | It's a shortcut for:
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| 36 |
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| 37 | call myflags->append('-c')
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| 38 | call myflags->append('echo hi')
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| 39 |
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| 40 | Similar names: [append][]
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| 41 |
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| 42 | [append]: chap-index.html#append
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| 43 |
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| 44 | ### pp
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| 45 |
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| 46 | The `pp` builtin pretty prints values and interpreter state.
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| 47 |
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| 48 | Pretty printing expressions is the most common:
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| 49 |
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| 50 | $ var x = 42
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| 51 | $ pp (x + 5)
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| 52 | myfile.ysh:1: (Int) 47 # print value with code location
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| 53 |
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| 54 | You can pass an unevaluated expression:
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| 55 |
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| 56 | $ pp [x + 5]
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| 57 | myfile.ysh:1: (Int) 47 # evaluate first
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| 58 |
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| 59 | The `value` command is a synonym for the interactive `=` operator:
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| 60 |
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| 61 | $ pp value (x)
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| 62 | (Int) 42
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| 63 |
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| 64 | $ = x
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| 65 | (Int) 42
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| 66 |
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| 67 | Print proc names and doc comments:
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| 68 |
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| 69 | $ pp proc # subject to change
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| 70 |
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| 71 | You can also print low-level interpreter state. The trailing `_` indicates
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| 72 | that the exact format may change:
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| 73 |
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| 74 | Examples:
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| 75 |
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| 76 | $ var x = :| one two |
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| 77 |
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| 78 | $ pp asdl_ (x) # dump the ASDL "guts"
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| 79 |
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| 80 | $ pp test_ (x) # single-line stable format, for spec tests
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| 81 |
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| 82 | # dump the ASDL representation of a "Cell", which is a location for a value
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| 83 | # (not the value itself)
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| 84 | $ pp cell_ x
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| 85 |
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| 86 |
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| 87 | ## Handle Errors
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| 88 |
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| 89 | ### error
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| 90 |
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| 91 | The `error` builtin interrupts shell execution.
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| 92 |
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| 93 | If there's a surrounding `try` block, the `_error` register is set, and
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| 94 | execution proceeds after the block.
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| 95 |
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| 96 | Otherwise, the shell exits with a non-zero status.
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| 97 |
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| 98 | Examples:
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| 99 |
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| 100 | error 'Missing /tmp' # program fails with status 10
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| 101 |
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| 102 | try {
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| 103 | error 'Another problem'
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| 104 | }
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| 105 | echo $[error.code] # => 10
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| 106 |
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| 107 | Override the default error code of `10` with a named argument:
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| 108 |
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| 109 | error 'Missing /tmp' (code=99) # program fails with status 99
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| 110 |
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| 111 | Named arguments add arbitrary properties to the resulting `_error` register:
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| 112 |
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| 113 | error 'Oops' (path='foo.json')
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| 114 |
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| 115 | See [YSH Error Handling](../ysh-error-handling.html) for more examples.
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| 116 |
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| 117 | ### failed
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| 118 |
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| 119 | A shortcut for `(_error.code !== 0)`:
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| 120 |
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| 121 | try {
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| 122 | ls /tmp
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| 123 | }
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| 124 | if failed {
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| 125 | echo 'ls failed'
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| 126 | }
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| 127 |
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| 128 | It saves you 7 punctuation characters: `( _ . !== )`
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| 129 |
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| 130 | See [YSH Error Handling](../ysh-error-handling.html) for more examples.
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| 131 |
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| 132 | ### try
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| 133 |
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| 134 | Run a block of code, stopping at the first error. (This is implemented with
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| 135 | `shopt --set errexit`)
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| 136 |
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| 137 | `try` sets the `_error` register to a dict, and always returns 0.
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| 138 |
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| 139 | try {
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| 140 | ls /nonexistent
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| 141 | }
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| 142 | if (_error.code !== 0) {
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| 143 | echo 'ls failed'
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| 144 | }
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| 145 |
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| 146 | Handle expression errors:
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| 147 |
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| 148 | try {
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| 149 | var x = 42 / 0
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| 150 | }
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| 151 |
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| 152 | And errors from compound commands:
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| 153 |
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| 154 | try {
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| 155 | ls | wc -l
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| 156 | diff <(sort left.txt) <(sort right.txt)
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| 157 | }
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| 158 |
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| 159 | The case statement can be useful:
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| 160 |
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| 161 | try {
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| 162 | grep PATTERN FILE.txt
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| 163 | }
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| 164 | case (_error.code) {
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| 165 | (0) { echo 'found' }
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| 166 | (1) { echo 'not found' }
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| 167 | (else) { echo "grep returned status $[_error.code]" }
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| 168 | }
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| 169 |
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| 170 | See [YSH Error Handling](../ysh-error-handling.html) for more examples.
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| 171 |
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| 172 | ### boolstatus
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| 173 |
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| 174 | Runs a command, and requires the exit code to be 0 or 1.
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| 175 |
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| 176 | if boolstatus egrep '[0-9]+' myfile { # e.g. aborts on status 2
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| 177 | echo 'found' # status 0 means found
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| 178 | } else {
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| 179 | echo 'not found' # status 1 means not found
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| 180 | }
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| 181 |
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| 182 | It's meant for external commands that "return" more than 2 values, like true /
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| 183 | false / fail, rather than pass / fail.
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| 184 |
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| 185 | ### assert
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| 186 |
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| 187 | Evaluates and expression, and fails if it is not truthy.
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| 188 |
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| 189 | assert (false) # fails
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| 190 | assert [false] # also fails (the expression is evaluated)
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| 191 |
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| 192 | It's common to pass an unevaluated expression with `===`:
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| 193 |
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| 194 | func f() { return (42) }
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| 195 |
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| 196 | assert [43 === f()]
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| 197 |
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| 198 | In this special case, you get a nicer error message:
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| 199 |
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| 200 | > Expected: 43
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| 201 | > Got: 42
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| 202 |
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| 203 | That is, the left-hand side should be the expected value, and the right-hand
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| 204 | side should be the actual value.
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| 205 |
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| 206 | ## Shell State
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| 207 |
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| 208 | ### ysh-cd
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| 209 |
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| 210 | It takes a block:
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| 211 |
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| 212 | cd / {
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| 213 | echo $PWD
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| 214 | }
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| 215 |
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| 216 | ### ysh-shopt
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| 217 |
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| 218 | It takes a block:
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| 219 |
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| 220 | shopt --unset errexit {
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| 221 | false
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| 222 | echo 'ok'
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| 223 | }
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| 224 |
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| 225 | ### shvar
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| 226 |
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| 227 | Execute a block with a global variable set.
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| 228 |
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| 229 | shvar IFS=/ {
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| 230 | echo "ifs is $IFS"
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| 231 | }
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| 232 | echo "ifs restored to $IFS"
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| 233 |
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| 234 | ### ctx
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| 235 |
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| 236 | Execute a block with a shared "context" that can be updated using the `ctx`
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| 237 | built-in.
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| 238 |
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| 239 | var mydict = {}
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| 240 | ctx push (mydict) {
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| 241 | # = mydict => {}
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| 242 | ctx set (mykey='myval')
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| 243 | }
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| 244 | # = mydict => { mykey: 'myval' }
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| 245 |
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| 246 | The context can be modified with `ctx set (key=val)`, which updates or inserts
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| 247 | the value at the given key.
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| 248 |
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| 249 | The context can also be updated with `ctx emit field (value)`.
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| 250 |
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| 251 | ctx push (mydict) {
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| 252 | # = mydict => {}
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| 253 | ctx emit mylist (0)
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| 254 | # = mydict => { mylist: [0] }
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| 255 | ctx emit mylist (1)
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| 256 | }
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| 257 | # = mydict => { mylist: [0, 1] }
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| 258 |
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| 259 | Contexts can be nested, resulting in a stack of contexts.
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| 260 |
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| 261 | ctx push (mydict1) {
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| 262 | ctx set (dict=1)
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| 263 | ctx push (mydict2) {
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| 264 | ctx set (dict=2)
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| 265 | }
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| 266 | }
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| 267 | # = mydict1 => { dict: 1 }
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| 268 | # = mydict2 => { dict: 2 }
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| 269 |
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| 270 | `ctx` is useful for creating DSLs, such as a mini-parseArgs.
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| 271 |
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| 272 | proc parser (; place ; ; block_def) {
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| 273 | var p = {}
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| 274 | ctx push (p, block_def)
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| 275 | call place->setValue(p)
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| 276 | }
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| 277 |
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| 278 | proc flag (short_name, long_name; type; help) {
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| 279 | ctx emit flag ({short_name, long_name, type, help})
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| 280 | }
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| 281 |
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| 282 | proc arg (name) {
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| 283 | ctx emit arg ({name})
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| 284 | }
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| 285 |
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| 286 | parser (&spec) {
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| 287 | flag -t --tsv (Bool, help='Output as TSV')
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| 288 | flag -r --recursive (Bool, help='Recurse into the given directory')
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| 289 | flag -N --count (Int, help='Process no more than N files')
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| 290 | arg path
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| 291 | }
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| 292 |
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| 293 | ### push-registers
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| 294 |
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| 295 | Save global registers like $? on a stack. It's useful for preventing plugins
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| 296 | from interfering with user code. Example:
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| 297 |
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| 298 | status_42 # returns 42 and sets $?
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| 299 | push-registers { # push a new frame
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| 300 | status_43 # top of stack changed here
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| 301 | echo done
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| 302 | } # stack popped
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| 303 | echo $? # 42, read from new top-of-stack
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| 304 |
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| 305 | Current list of registers:
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| 306 |
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| 307 | Regex data underlying BASH_REMATCH, _group(), _start(), _end()
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| 308 | $?
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| 309 | _error # set by the try builtin
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| 310 | PIPESTATUS # aka _pipeline_status
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| 311 | _process_sub_status
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| 312 |
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| 313 |
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| 314 | ## Modules
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| 315 |
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| 316 | ### runproc
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| 317 |
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| 318 | Runs a named proc with the given arguments. It's often useful as the only top
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| 319 | level statement in a "task file":
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| 320 |
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| 321 | proc p {
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| 322 | echo hi
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| 323 | }
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| 324 | runproc @ARGV
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| 325 |
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| 326 | Like 'builtin' and 'command', it affects the lookup of the first word.
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| 327 |
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| 328 | ### source-guard
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| 329 |
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| 330 | Registers a name in the global "module" dict. Returns 0 if it doesn't exist,
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| 331 | or 1 if it does.
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| 332 |
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| 333 | Use it like this in executable files:
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| 334 |
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| 335 | source-guard main || return 0
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| 336 |
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| 337 | And like this in libraries:
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| 338 |
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| 339 | source-guard myfile.ysh || return 0
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| 340 |
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| 341 | ### is-main
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| 342 |
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| 343 | The `is-main` builtin returns 1 (false) if the current file was executed with
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| 344 | the `source` builtin.
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| 345 |
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| 346 | In the "main" file, including `-c` or `stdin` input, it returns 0 (true).
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| 347 |
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| 348 | Use it like this:
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| 349 |
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| 350 | if is-main {
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| 351 | runproc @ARGV
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| 352 | }
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| 353 |
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| 354 | ### use
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| 355 |
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| 356 | Import code from other files, creating an `Obj` that acts like a namespace.
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| 357 |
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| 358 | use my-dir/my-module.ysh
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| 359 |
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| 360 | echo $[my_module.my_integer] # the module Obj has attributes
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| 361 | my_module myproc # the module Obj is invokable
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| 362 |
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| 363 | The evaluation of such files is cached, so it won't be re-evaluated if `use` is called again.
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| 364 |
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| 365 | <!--
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| 366 | # TODO: implicit $_this_dir aka relative import?
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| 367 |
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| 368 | That makes scripts callable from elsewhere?
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| 369 | -->
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| 370 |
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| 371 | <!--
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| 372 | Bind a specific name:
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| 373 |
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| 374 | use lib/foo.ysh (&myvar) # makes 'myvar' available
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| 375 |
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| 376 | Bind multiple names:
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| 377 |
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| 378 | use lib/foo.ysh (&myvar) {
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| 379 | pick log die
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| 380 | }
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| 381 |
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| 382 | Maybe:
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| 383 |
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| 384 | use lib/foo.ysh (&myvar) {
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| 385 | pick log (&mylog)
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| 386 | pick die (&mydie)
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| 387 | }
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| 388 | -->
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| 389 |
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| 390 | The `--extern` flag make the invocation do nothing. It can be used be tools to
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| 391 | analyze what names are in the file.
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| 392 |
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| 393 | use --extern grep sed awk
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| 394 |
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| 395 | ## I/O
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| 396 |
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| 397 | ### ysh-read
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| 398 |
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| 399 | YSH adds long flags to shell's `read`:
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| 400 |
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| 401 | read --all # whole file including trailing \n, fills $_reply
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| 402 | read --all (&x) # fills $x
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| 403 |
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| 404 | read --num-bytes 3 # read N bytes, fills _reply
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| 405 | read --num-bytes 3 (&x) # fills $x
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| 406 |
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| 407 | read --raw-line # unbuffered read of line, omitting trailing \n
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| 408 | read --raw-line (&x) # fills $x
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| 409 |
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| 410 | read --raw-line --with-eol # include the trailing \n
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| 411 |
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| 412 | And a convenience:
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| 413 |
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| 414 | read -0 # read until NUL, synonym for read -r -d ''
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| 415 |
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| 416 | You may want to use `fromJson8()` or `fromJson()` after reading a line.
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| 417 |
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| 418 | <!--
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| 419 |
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| 420 | TODO:
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| 421 |
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| 422 | - read --netstr
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| 423 | - fromJ8Line() is different than from Json8! It's like @()
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| 424 |
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| 425 | -->
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| 426 |
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| 427 | <!--
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| 428 |
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| 429 | Problem with read --json -- there's also https://jsonlines.org, which allows
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| 430 |
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| 431 | {"my": "line"}
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| 432 |
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| 433 | That can be done with
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| 434 |
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| 435 | while read --line {
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| 436 | var record = fromJson(_reply)
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| 437 | }
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| 438 |
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| 439 | This is distinct from:
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| 440 |
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| 441 | while read --line --j8 {
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| 442 | echo $_reply
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| 443 | }
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| 444 |
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| 445 | This allows unquoted. Maybe it should be read --j8-line
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| 446 |
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| 447 | What about write? These would be the same:
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| 448 |
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| 449 | write --json -- $s
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| 450 | write --j8 -- $s
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| 451 |
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| 452 | write -- $[toJson(s)]
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| 453 | write -- $[toJson8(s)]
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| 454 |
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| 455 | write --json -- @strs
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| 456 | write --j8 -- @strs
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| 457 |
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| 458 | write -- @[toJson(s) for s in strs]
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| 459 | write -- @[toJson8(s) for s in strs]
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| 460 |
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| 461 | It's an argument for getting rid --json and --j8? I already implemented them,
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| 462 | but it makes the API smaller.
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| 463 |
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| 464 | I guess the main thing would be to AVOID quoting sometimes?
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| 465 |
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| 466 | $ write --j8 -- unquoted
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| 467 | unquoted
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| 468 |
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| 469 | $ write --j8 -- $'\'' '"'
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| 470 | "'"
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| 471 | "\""
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| 472 |
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| 473 | I think this could be the shell style?
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| 474 |
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| 475 | $ write --shell-str -- foo bar baz
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| 476 |
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| 477 | Or it could be
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| 478 |
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| 479 | $ write -- @[toShellString(s) for s in strs]
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| 480 |
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| 481 | I want this to be "J8 Lines", but it can be done in pure YSH. It's not built
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| 482 | into the interpreter.
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| 483 |
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| 484 | foo/bar
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| 485 | "hi"
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| 486 | b'hi'
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| 487 | u'hi'
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| 488 |
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| 489 | But what about
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| 490 |
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| 491 | Fool's Gold
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| 492 | a'hi' # This feels like an error?
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| 493 | a"hi" # what about this?
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| 494 |
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| 495 | Technically we CAN read those as literal strings
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| 496 | -->
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| 497 |
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| 498 | ### ysh-echo
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| 499 |
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| 500 | Print arguments to stdout, separated by a space.
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| 501 |
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| 502 | ysh$ echo hi there
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| 503 | hi there
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| 504 |
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| 505 | The [simple_echo][] option means that flags aren't accepted, and `--` is not
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| 506 | accepted.
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| 507 |
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| 508 | ysh$ echo -n
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| 509 | -n
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| 510 |
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| 511 | See the [YSH FAQ][echo-en] for details.
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| 512 |
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| 513 | [simple_echo]: chap-option.html#ysh:all
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| 514 | [echo-en]: ../ysh-faq.html#how-do-i-write-the-equivalent-of-echo-e-or-echo-n
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| 515 |
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| 516 | ### write
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| 517 |
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| 518 | write fixes problems with shell's `echo` builtin.
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| 519 |
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| 520 | The default separator is a newline, and the default terminator is a
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| 521 | newline.
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| 522 |
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| 523 | Examples:
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| 524 |
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| 525 | write -- ale bean # write two lines
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| 526 |
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| 527 | write -n -- ale bean # synonym for --end '', like echo -n
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| 528 | write --sep '' --end '' -- a b # write 2 bytes
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| 529 | write --sep $'\t' --end $'\n' -- a b # TSV line
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| 530 |
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| 531 | You may want to use `toJson8()` or `toJson()` before writing:
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| 532 |
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| 533 | write -- $[toJson8(mystr)]
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| 534 | write -- $[toJson(mystr)]
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| 535 |
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| 536 |
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| 537 | <!--
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| 538 | write --json -- ale bean # JSON encode, guarantees two lines
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| 539 | write --j8 -- ale bean # J8 encode, guarantees two lines
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| 540 | -->
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| 541 |
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| 542 |
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| 543 | ### fork
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| 544 |
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| 545 | Run a command, but don't wait for it to finish.
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| 546 |
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| 547 | fork { sleep 1 }
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| 548 | wait -n
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| 549 |
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| 550 | In YSH, use `fork` rather than shell's `&` ([ampersand][]).
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| 551 |
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| 552 | [ampersand]: chap-cmd-lang.html#ampersand
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| 553 |
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| 554 | ### forkwait
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| 555 |
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| 556 | The preferred alternative to shell's `()`. Prefer `cd` with a block if possible.
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| 557 |
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| 558 | forkwait {
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| 559 | not_mutated=zzz
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| 560 | }
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| 561 | echo $not_mutated
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| 562 |
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| 563 | ### fopen
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| 564 |
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| 565 | Runs a block passed to it. It's designed so redirects have a **prefix**
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| 566 | syntax:
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| 567 |
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| 568 | fopen >out.txt {
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| 569 | echo 1
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| 570 | echo 2
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| 571 | }
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| 572 |
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| 573 | Rather than shell style:
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| 574 |
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| 575 | { echo 1
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| 576 | echo 2
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| 577 | } >out.txt
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| 578 |
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| 579 | When a block is long, the former is more readable.
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| 580 |
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| 581 | ## Hay Config
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| 582 |
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| 583 | ### hay
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| 584 |
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| 585 | ### haynode
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| 586 |
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| 587 |
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| 588 | ## Data Formats
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| 589 |
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| 590 | ### json
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| 591 |
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| 592 | Write JSON:
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| 593 |
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| 594 | var d = {name: 'bob', age: 42}
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| 595 | json write (d) # default indentation of 2
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| 596 | json write (d, space=0) # no indentation
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| 597 |
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| 598 | Read JSON:
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| 599 |
|
| 600 | echo hi | json read # fills $_reply by default
|
| 601 |
|
| 602 | Or use an explicit place:
|
| 603 |
|
| 604 | var x = ''
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| 605 | json read (&x) < myfile.txt
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| 606 |
|
| 607 | Related: [err-json-encode][] and [err-json-decode][]
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| 608 |
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| 609 | [err-json-encode]: chap-errors.html#err-json-encode
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| 610 | [err-json-decode]: chap-errors.html#err-json-decode
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| 611 |
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| 612 | ### json8
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| 613 |
|
| 614 | Like `json`, but on the encoding side:
|
| 615 |
|
| 616 | - Falls back to `b'\yff'` instead of lossy Unicode replacement char
|
| 617 |
|
| 618 | On decoding side:
|
| 619 |
|
| 620 | - Understands `b'' u''` strings
|
| 621 |
|
| 622 | Related: [err-json8-encode]() and [err-json8-decode]()
|
| 623 |
|
| 624 | [err-json8-encode]: chap-errors.html#err-json8-encode
|
| 625 | [err-json8-decode]: chap-errors.html#err-json8-decode
|
| 626 |
|
| 627 | ## Testing
|
| 628 |
|
| 629 | TODO: describe
|
| 630 |
|
| 631 | ## External Lang
|
| 632 |
|
| 633 | TODO: when
|
| 634 |
|
| 635 |
|
| 636 | ## I/O
|
| 637 |
|
| 638 | These builtins take input and output. They're often used with redirects.
|
| 639 |
|
| 640 | ### read
|
| 641 |
|
| 642 | read FLAG* VAR*
|
| 643 |
|
| 644 | Read a line from stdin, split it into tokens with the `$IFS` algorithm,
|
| 645 | and assign the tokens to the given variables. When no VARs are given,
|
| 646 | assign to `$REPLY`.
|
| 647 |
|
| 648 | Note: When writing ySH, prefer the extensions documented in
|
| 649 | [ysh-read](#ysh-read). The `read` builtin is confusing because `-r` needs to
|
| 650 | be explicitly enabled.
|
| 651 |
|
| 652 | Flags:
|
| 653 |
|
| 654 | -a ARRAY assign the tokens to elements of this array
|
| 655 | -d CHAR use DELIM as delimiter, instead of newline
|
| 656 | -n NUM read up to NUM characters, respecting delimiters
|
| 657 | -p STR print the string PROMPT before reading input
|
| 658 | -r raw mode: don't let backslashes escape characters
|
| 659 | -s silent: do not echo input coming from a terminal
|
| 660 | -t NUM time out and fail after TIME seconds
|
| 661 | -t 0 returns whether any input is available
|
| 662 | -u FD read from file descriptor FD instead of 0 (stdin)
|
| 663 |
|
| 664 | <!-- -N NUM read up to NUM characters, ignoring delimiters -->
|
| 665 | <!-- -e use readline to obtain the line
|
| 666 | -i STR use STR as the initial text for readline -->
|
| 667 |
|
| 668 | ### echo
|
| 669 |
|
| 670 | echo FLAG* ARG*
|
| 671 |
|
| 672 | Prints ARGs to stdout, separated by a space, and terminated by a newline.
|
| 673 |
|
| 674 | Flags:
|
| 675 |
|
| 676 | -e enable interpretation of backslash escapes
|
| 677 | -n omit the trailing newline
|
| 678 | <!-- -E -->
|
| 679 |
|
| 680 | See [char-escapes](chap-mini-lang.html#char-escapes).
|
| 681 |
|
| 682 | ### printf
|
| 683 |
|
| 684 | printf FLAG* FMT ARG*
|
| 685 |
|
| 686 | Formats values and prints them. The FMT string contain three types of objects:
|
| 687 |
|
| 688 | 1. Literal Characters
|
| 689 | 2. Character escapes like `\t`. See [char-escapes](chap-mini-lang.html#char-escapes).
|
| 690 | 3. Percent codes like `%s` that specify how to format each each ARG.
|
| 691 |
|
| 692 | If not enough ARGS are passed, the empty string is used. If too many are
|
| 693 | passed, the FMT string will be "recycled".
|
| 694 |
|
| 695 | Flags:
|
| 696 |
|
| 697 | -v VAR Write output in variable VAR instead of standard output.
|
| 698 |
|
| 699 | Format specifiers:
|
| 700 |
|
| 701 | %% Prints a single "%".
|
| 702 | %b Interprets backslash escapes while printing.
|
| 703 | %q Prints the argument escaping the characters needed to make it reusable
|
| 704 | as shell input.
|
| 705 | %d Print as signed decimal number.
|
| 706 | %i Same as %d.
|
| 707 | %o Print as unsigned octal number.
|
| 708 | %u Print as unsigned decimal number.
|
| 709 | %x Print as unsigned hexadecimal number with lower-case hex-digits (a-f).
|
| 710 | %X Same as %x, but with upper-case hex-digits (A-F).
|
| 711 | %f Print as floating point number.
|
| 712 | %e Print as a double number, in "±e" format (lower-case e).
|
| 713 | %E Same as %e, but with an upper-case E.
|
| 714 | %g Interprets the argument as double, but prints it like %f or %e.
|
| 715 | %G Same as %g, but print it like %E.
|
| 716 | %c Print as a single char, only the first character is printed.
|
| 717 | %s Print as string
|
| 718 | %n The number of characters printed so far is stored in the variable named
|
| 719 | in the argument.
|
| 720 | %a Interprets the argument as double, and prints it like a C99 hexadecimal
|
| 721 | floating-point literal.
|
| 722 | %A Same as %a, but print it like %E.
|
| 723 | %(FORMAT)T Prints date and time, according to FORMAT as a format string
|
| 724 | for strftime(3). The argument is the number of seconds since
|
| 725 | epoch. It can also be -1 (current time, also the default value
|
| 726 | if there is no argument) or -2 (shell startup time).
|
| 727 |
|
| 728 | ### readarray
|
| 729 |
|
| 730 | Alias for `mapfile`.
|
| 731 |
|
| 732 | ### mapfile
|
| 733 |
|
| 734 | mapfile FLAG* ARRAY?
|
| 735 |
|
| 736 | Reads lines from stdin into the variable named ARRAY (default
|
| 737 | `${MAPFILE[@]}`).
|
| 738 |
|
| 739 | Flags:
|
| 740 |
|
| 741 | -t Remove the trailing newline from every line
|
| 742 | <!--
|
| 743 | -d CHAR use CHAR as delimiter, instead of the default newline
|
| 744 | -n NUM copy up to NUM lines
|
| 745 | -O NUM begins copying lines at the NUM element of the array
|
| 746 | -s NUM discard the first NUM lines
|
| 747 | -u FD read from FD file descriptor instead of the standard input
|
| 748 | -C CMD run CMD every NUM lines specified in -c
|
| 749 | -c NUM every NUM lines, the CMD command in C will be run
|
| 750 | -->
|
| 751 |
|
| 752 | ## Run Code
|
| 753 |
|
| 754 | These builtins accept shell code and run it.
|
| 755 |
|
| 756 | ### source
|
| 757 |
|
| 758 | source SCRIPT ARG*
|
| 759 |
|
| 760 | Execute SCRIPT with the given ARGs, in the context of the current shell. That is,
|
| 761 | existing variables will be modified.
|
| 762 |
|
| 763 | ---
|
| 764 |
|
| 765 | Oils extension: If the SCRIPT starts with `///`, we look for scripts embedded in
|
| 766 | the `oils-for-unix` binary. Example:
|
| 767 |
|
| 768 | source ///osh/two.sh # load embedded script
|
| 769 |
|
| 770 | : ${LIB_OSH=fallback/dir}
|
| 771 | source $LIB_OSH/two.sh # same thing
|
| 772 |
|
| 773 | The [LIB_OSH][] form is useful for writing a script that works under both bash
|
| 774 | and OSH.
|
| 775 |
|
| 776 | - Related: the [cat-em][] tool prints embedded scripts.
|
| 777 |
|
| 778 | [LIB_OSH]: chap-special-var.html#LIB_OSH
|
| 779 | [cat-em]: chap-front-end.html#cat-em
|
| 780 |
|
| 781 |
|
| 782 | ### eval
|
| 783 |
|
| 784 | eval ARG+
|
| 785 |
|
| 786 | Creates a string by joining ARGs with a space, then runs it as a shell command.
|
| 787 |
|
| 788 | Example:
|
| 789 |
|
| 790 | # Create the string echo "hello $name" and run it.
|
| 791 | a='echo'
|
| 792 | b='"hello $name"'
|
| 793 | eval $a $b
|
| 794 |
|
| 795 | Tips:
|
| 796 |
|
| 797 | - Using `eval` can confuse code and user-supplied data, leading to [security
|
| 798 | issues][].
|
| 799 | - Prefer passing single string ARG to `eval`.
|
| 800 |
|
| 801 | [security issues]: https://mywiki.wooledge.org/BashFAQ/048
|
| 802 |
|
| 803 | ### trap
|
| 804 |
|
| 805 | trap FLAG* CMD SIGNAL*
|
| 806 |
|
| 807 | Registers the shell string CMD to be run after the SIGNALs are received. If
|
| 808 | the CMD is empty, then the signal is ignored.
|
| 809 |
|
| 810 | Flags:
|
| 811 |
|
| 812 | -l Lists all signals and their signal number
|
| 813 | -p Prints a list of the installed signal handlers
|
| 814 |
|
| 815 | Tip:
|
| 816 |
|
| 817 | Prefer passing the name of a shell function to `trap`.
|
| 818 |
|
| 819 | ## Set Options
|
| 820 |
|
| 821 | The `set` and `shopt` builtins set global shell options. YSH code should use
|
| 822 | the more natural `shopt`.
|
| 823 |
|
| 824 | ### set
|
| 825 |
|
| 826 | set FLAG* ARG*
|
| 827 |
|
| 828 | Sets global shell options. Short style:
|
| 829 |
|
| 830 | set -e
|
| 831 |
|
| 832 | Long style:
|
| 833 |
|
| 834 | set -o errexit
|
| 835 |
|
| 836 | Set the arguments array:
|
| 837 |
|
| 838 | set -- 1 2 3
|
| 839 |
|
| 840 | ### shopt
|
| 841 |
|
| 842 | shopt FLAG* OPTION* BLOCK?
|
| 843 |
|
| 844 | Sets global shell options.
|
| 845 |
|
| 846 | Flags:
|
| 847 |
|
| 848 | -s --set Turn the named options on
|
| 849 | -u --unset Turn the named options off
|
| 850 | -p Print option values
|
| 851 | -o Use older set of options, normally controlled by 'set -o'
|
| 852 | -q Return 0 if the option is true, else 1
|
| 853 |
|
| 854 | Examples:
|
| 855 |
|
| 856 | shopt --set errexit
|
| 857 |
|
| 858 | You can set or unset multiple options with the groups `strict:all`,
|
| 859 | `ysh:upgrade`, and `ysh:all`.
|
| 860 |
|
| 861 | If a block is passed, then the mutated options are pushed onto a stack, the
|
| 862 | block is executed, and then options are restored to their original state.
|
| 863 |
|
| 864 | ## Working Dir
|
| 865 |
|
| 866 | These 5 builtins deal with the working directory of the shell.
|
| 867 |
|
| 868 | ### cd
|
| 869 |
|
| 870 | cd FLAG* DIR
|
| 871 |
|
| 872 | Changes the working directory of the current shell process to DIR.
|
| 873 |
|
| 874 | If DIR isn't specified, change to `$HOME`. If DIR is `-`, change to `$OLDPWD`
|
| 875 | (a variable that the sets to the previous working directory.)
|
| 876 |
|
| 877 | Flags:
|
| 878 |
|
| 879 | -L Follow symbolic links, i.e. change to the TARGET of the symlink.
|
| 880 | (default).
|
| 881 | -P Don't follow symbolic links.
|
| 882 |
|
| 883 | ### pwd
|
| 884 |
|
| 885 | pwd FLAG*
|
| 886 |
|
| 887 | Prints the current working directory.
|
| 888 |
|
| 889 | Flags:
|
| 890 |
|
| 891 | -L Follow symbolic links if present (default)
|
| 892 | -P Don't follow symbolic links. Print the link instead of the target.
|
| 893 |
|
| 894 | ### pushd
|
| 895 |
|
| 896 | <!--pushd FLAGS DIR-->
|
| 897 | pushd DIR
|
| 898 | <!--pushd +/-NUM-->
|
| 899 |
|
| 900 | Add DIR to the directory stack, then change the working directory to DIR.
|
| 901 | Typically used with `popd` and `dirs`.
|
| 902 |
|
| 903 | <!--FLAGS:
|
| 904 | -n Don't change the working directory, just manipulate the stack
|
| 905 | NUM:
|
| 906 | Rotates the stack the number of places specified. Eg, given the stack
|
| 907 | '/foo /bar /baz', where '/foo' is the top of the stack, pushd +1 will move
|
| 908 | it to the bottom, '/bar /baz /foo'-->
|
| 909 |
|
| 910 | ### popd
|
| 911 |
|
| 912 | popd
|
| 913 |
|
| 914 | Removes a directory from the directory stack, and changes the working directory
|
| 915 | to it. Typically used with `pushd` and `dirs`.
|
| 916 |
|
| 917 | ### dirs
|
| 918 |
|
| 919 | dirs FLAG*
|
| 920 |
|
| 921 | Shows the contents of the directory stack. Typically used with `pushd` and
|
| 922 | `popd`.
|
| 923 |
|
| 924 | Flags:
|
| 925 |
|
| 926 | -c Clear the dir stack.
|
| 927 | -l Show the dir stack, but with the real path instead of ~.
|
| 928 | -p Show the dir stack, but formatted as one line per entry.
|
| 929 | -v Like -p, but numbering each line.
|
| 930 |
|
| 931 | ## Completion
|
| 932 |
|
| 933 | These builtins implement our bash-compatible autocompletion system.
|
| 934 |
|
| 935 | ### complete
|
| 936 |
|
| 937 | Registers completion policies for different commands.
|
| 938 |
|
| 939 | ### compgen
|
| 940 |
|
| 941 | Generates completion candidates inside a user-defined completion function.
|
| 942 |
|
| 943 | It can also be used in scripts, i.e. outside a completion function.
|
| 944 |
|
| 945 | ### compopt
|
| 946 |
|
| 947 | Changes completion options inside a user-defined completion function.
|
| 948 |
|
| 949 | ### compadjust
|
| 950 |
|
| 951 | Adjusts `COMP_ARGV` according to specified delimiters, and optionally set
|
| 952 | variables cur, prev, words (an array), and cword. May also set 'split'.
|
| 953 |
|
| 954 | This is an OSH extension that makes it easier to run the bash-completion
|
| 955 | project.
|
| 956 |
|
| 957 | ### compexport
|
| 958 |
|
| 959 | Complete an entire shell command string. For example,
|
| 960 |
|
| 961 | compexport -c 'echo $H'
|
| 962 |
|
| 963 | will complete variables like `$HOME`. And
|
| 964 |
|
| 965 | compexport -c 'ha'
|
| 966 |
|
| 967 | will complete builtins like `hay`, as well as external commands.
|
| 968 |
|
| 969 |
|
| 970 | ## Shell Process
|
| 971 |
|
| 972 | These builtins mutate the state of the shell process.
|
| 973 |
|
| 974 | ### exec
|
| 975 |
|
| 976 | exec BIN_PATH ARG*
|
| 977 |
|
| 978 | Replaces the running shell with the binary specified, which is passed ARGs.
|
| 979 | BIN_PATH must exist on the file system; i.e. it can't be a shell builtin or
|
| 980 | function.
|
| 981 |
|
| 982 | ### umask
|
| 983 |
|
| 984 | umask MODE?
|
| 985 |
|
| 986 | Sets the bit mask that determines the permissions for new files and
|
| 987 | directories. The mask is subtracted from 666 for files and 777 for
|
| 988 | directories.
|
| 989 |
|
| 990 | Oils currently supports writing masks in octal.
|
| 991 |
|
| 992 | If no MODE, show the current mask.
|
| 993 |
|
| 994 | ### ulimit
|
| 995 |
|
| 996 | ulimit --all
|
| 997 | ulimit -a
|
| 998 | ulimit FLAGS* -RESOURCE_FLAG VALUE?
|
| 999 |
|
| 1000 | ulimit FLAGS* VALUE? # discouraged
|
| 1001 |
|
| 1002 | Show and modify process resource limits.
|
| 1003 |
|
| 1004 | Flags:
|
| 1005 |
|
| 1006 | -S for soft limit
|
| 1007 | -H for hard limit
|
| 1008 |
|
| 1009 | -c -d -f ... # ulimit --all shows all resource flags
|
| 1010 |
|
| 1011 | Show a table of resources:
|
| 1012 |
|
| 1013 | ulimit --all
|
| 1014 | ulimit -a
|
| 1015 |
|
| 1016 | For example, the table shows that `-n` is the flag that controls the number
|
| 1017 | file descriptors, the soft and hard limit for `-n`, and the multiplication
|
| 1018 | "factor" for the integer VALUE you pass.
|
| 1019 |
|
| 1020 | ---
|
| 1021 |
|
| 1022 | Here are examples of using resource flags.
|
| 1023 |
|
| 1024 | Get the soft limit for the number of file descriptors:
|
| 1025 |
|
| 1026 | ulimit -S -n
|
| 1027 | ulimit -n # same thing
|
| 1028 |
|
| 1029 | Get the hard limit:
|
| 1030 |
|
| 1031 | ulimit -H -n
|
| 1032 |
|
| 1033 | Set the soft or hard limit:
|
| 1034 |
|
| 1035 | ulimit -S -n 100
|
| 1036 | ulimit -H -n 100
|
| 1037 |
|
| 1038 | Set both limits:
|
| 1039 |
|
| 1040 | ulimit -n 100
|
| 1041 |
|
| 1042 | A special case that's discouraged: with no resource flag, `-f` is assumed:
|
| 1043 |
|
| 1044 | ulimit # equivalent to ulimit -f
|
| 1045 | ulimit 100 # equivalent to ulimit -f 100
|
| 1046 |
|
| 1047 | ### times
|
| 1048 |
|
| 1049 | times
|
| 1050 |
|
| 1051 | Shows the user and system time used by the shell and its child processes.
|
| 1052 |
|
| 1053 | ## Child Process
|
| 1054 |
|
| 1055 | ### jobs
|
| 1056 |
|
| 1057 | jobs
|
| 1058 |
|
| 1059 | Shows all jobs running in the shell and their status.
|
| 1060 |
|
| 1061 | ### wait
|
| 1062 |
|
| 1063 | wait FLAG* ARG
|
| 1064 |
|
| 1065 | Wait for processes to exit.
|
| 1066 |
|
| 1067 | If the ARG is a PID, wait only for that job, and return its status.
|
| 1068 |
|
| 1069 | If there's no ARG, wait for all child processes.
|
| 1070 |
|
| 1071 | <!--
|
| 1072 | The ARG can be a PID (tracked by the kernel), or a job number (tracked by the
|
| 1073 | shell). Specify jobs with the syntax `%jobnumber`.
|
| 1074 | -->
|
| 1075 |
|
| 1076 | Flags:
|
| 1077 |
|
| 1078 | -n Wait for the next process to exit, rather than a specific process.
|
| 1079 |
|
| 1080 | Wait can be interrupted by a signal, in which case the exit code indicates the
|
| 1081 | signal number.
|
| 1082 |
|
| 1083 | ### fg
|
| 1084 |
|
| 1085 | fg JOB?
|
| 1086 |
|
| 1087 | Returns a job running in the background to the foreground. If no JOB is
|
| 1088 | specified, use the latest job.
|
| 1089 |
|
| 1090 | <!--<h4 id="bg">bg</h4>
|
| 1091 |
|
| 1092 | The bg builtin resumes suspend job, while keeping it in the background.
|
| 1093 |
|
| 1094 | bg JOB?
|
| 1095 |
|
| 1096 | JOB:
|
| 1097 | Job ID to be resumed in the background. If none is specified, the latest job
|
| 1098 | is chosen. -->
|
| 1099 |
|
| 1100 | ## External
|
| 1101 |
|
| 1102 | ### test
|
| 1103 |
|
| 1104 | test OP ARG
|
| 1105 | test ARG OP ARG
|
| 1106 | [ OP ARG ] # [ is an alias for test that requires closing ]
|
| 1107 | [ ARG OP ARG ]
|
| 1108 |
|
| 1109 | Evaluates a conditional expression and returns 0 (true) or 1 (false).
|
| 1110 |
|
| 1111 | Note that [ is the name of a builtin, not an operator in the language. Use
|
| 1112 | 'test' to avoid this confusion.
|
| 1113 |
|
| 1114 | String expressions:
|
| 1115 |
|
| 1116 | -n STR True if STR is not empty.
|
| 1117 | 'test STR' is usually equivalent, but discouraged.
|
| 1118 | -z STR True if STR is empty.
|
| 1119 | STR1 = STR2 True if the strings are equal.
|
| 1120 | STR1 != STR2 True if the strings are not equal.
|
| 1121 | STR1 < STR2 True if STR1 sorts before STR2 lexicographically.
|
| 1122 | STR1 > STR2 True if STR1 sorts after STR2 lexicographically.
|
| 1123 | Note: < and > should be quoted like \< and \>
|
| 1124 |
|
| 1125 | File expressions:
|
| 1126 |
|
| 1127 | -a FILE Synonym for -e.
|
| 1128 | -b FILE True if FILE is a block special file.
|
| 1129 | -c FILE True if FILE is a character special file.
|
| 1130 | -d FILE True if FILE is a directory.
|
| 1131 | -e FILE True if FILE exists.
|
| 1132 | -f FILE True if FILE is a regular file.
|
| 1133 | -g FILE True if FILE has the sgid bit set.
|
| 1134 | -G FILE True if current user's group is also FILE's group.
|
| 1135 | -h FILE True if FILE is a symbolic link.
|
| 1136 | -L FILE True if FILE is a symbolic link.
|
| 1137 | -k FILE True if FILE has the sticky bit set.
|
| 1138 | -O FILE True if current user is the file owner.
|
| 1139 | -p FILE True if FILE is a named pipe (FIFO).
|
| 1140 | -r FILE True if FILE is readable.
|
| 1141 | -s FILE True if FILE has size bigger than 0.
|
| 1142 | -S FILE True if FILE is a socket file.
|
| 1143 | -t FD True if file descriptor FD is open and refers to a terminal.
|
| 1144 | -u FILE True if FILE has suid bit set.
|
| 1145 | -w FILE True if FILE is writable.
|
| 1146 | -x FILE True if FILE is executable.
|
| 1147 | FILE1 -nt FILE2 True if FILE1 is newer than FILE2 (mtime).
|
| 1148 | FILE1 -ot FILE2 True if FILE1 is older than FILE2 (mtime).
|
| 1149 | FILE1 -ef FILE2 True if FILE1 is a hard link to FILE2.
|
| 1150 | <!-- -N FILE True if FILE was modified since last read (mtime newer than atime).-->
|
| 1151 |
|
| 1152 | Arithmetic expressions coerce arguments to integers, then compare:
|
| 1153 |
|
| 1154 | INT1 -eq INT2 True if they're equal.
|
| 1155 | INT1 -ne INT2 True if they're not equal.
|
| 1156 | INT1 -lt INT2 True if INT1 is less than INT2.
|
| 1157 | INT1 -le INT2 True if INT1 is less or equal than INT2.
|
| 1158 | INT1 -gt INT2 True if INT1 is greater than INT2.
|
| 1159 | INT1 -ge INT2 True if INT1 is greater or equal than INT2.
|
| 1160 |
|
| 1161 | Other expressions:
|
| 1162 |
|
| 1163 | -o OPTION True if the shell option OPTION is set.
|
| 1164 | -v VAR True if the variable VAR is set.
|
| 1165 |
|
| 1166 | The test builtin also supports POSIX conditionals like -a, -o, !, and ( ), but
|
| 1167 | these are discouraged.
|
| 1168 |
|
| 1169 | <!-- -R VAR True if the variable VAR has been set and is a nameref variable. -->
|
| 1170 |
|
| 1171 | Oils supports these long flags:
|
| 1172 |
|
| 1173 | --dir same as -d
|
| 1174 | --exists same as -e
|
| 1175 | --file same as -f
|
| 1176 | --symlink same as -L
|
| 1177 |
|
| 1178 | ### getopts
|
| 1179 |
|
| 1180 | getopts SPEC VAR ARG*
|
| 1181 |
|
| 1182 | A single iteration of flag parsing. The SPEC is a sequence of flag characters,
|
| 1183 | with a trailing `:` to indicate that the flag takes an argument:
|
| 1184 |
|
| 1185 | ab # accept -a and -b
|
| 1186 | xy:z # accept -x, -y arg, and -z
|
| 1187 |
|
| 1188 | The input is `"$@"` by default, unless ARGs are passed.
|
| 1189 |
|
| 1190 | On each iteration, the flag character is stored in VAR. If the flag has an
|
| 1191 | argument, it's stored in `$OPTARG`. When an error occurs, VAR is set to `?`
|
| 1192 | and `$OPTARG` is unset.
|
| 1193 |
|
| 1194 | Returns 0 if a flag is parsed, or 1 on end of input or another error.
|
| 1195 |
|
| 1196 | Example:
|
| 1197 |
|
| 1198 | while getopts "ab:" flag; do
|
| 1199 | case $flag in
|
| 1200 | a) flag_a=1 ;;
|
| 1201 | b) flag_b=$OPTARG" ;;
|
| 1202 | '?') echo 'Invalid Syntax'; break ;;
|
| 1203 | esac
|
| 1204 | done
|
| 1205 |
|
| 1206 | Notes:
|
| 1207 | - `$OPTIND` is initialized to 1 every time a shell starts, and is used to
|
| 1208 | maintain state between invocations of `getopts`.
|
| 1209 | - The characters `:` and `?` can't be flags.
|
| 1210 |
|
| 1211 | ### kill
|
| 1212 |
|
| 1213 | Unimplemented.
|
| 1214 |
|
| 1215 | <!-- Note: 'kill' accepts job control syntax -->
|
| 1216 |
|
| 1217 | ## Introspection
|
| 1218 |
|
| 1219 | <h3 id="help" class="osh-topic ysh-topic" oils-embed="1">
|
| 1220 | help
|
| 1221 | </h3>
|
| 1222 |
|
| 1223 | <!-- pre-formatted for help builtin -->
|
| 1224 |
|
| 1225 | ```
|
| 1226 | Usage: help TOPIC?
|
| 1227 |
|
| 1228 | Examples:
|
| 1229 |
|
| 1230 | help # this help
|
| 1231 | help echo # help on the 'echo' builtin
|
| 1232 | help command-sub # help on command sub $(date)
|
| 1233 |
|
| 1234 | help oils-usage # identical to oils-for-unix --help
|
| 1235 | help osh-usage # osh --help
|
| 1236 | help ysh-usage # ysh --help
|
| 1237 | ```
|
| 1238 |
|
| 1239 | ### hash
|
| 1240 |
|
| 1241 | hash
|
| 1242 |
|
| 1243 | Display information about remembered commands.
|
| 1244 |
|
| 1245 | hash FLAG* CMD+
|
| 1246 |
|
| 1247 | Determine the locations of commands using `$PATH`, and remember them.
|
| 1248 |
|
| 1249 | Flag:
|
| 1250 |
|
| 1251 | -r Discard all remembered locations.
|
| 1252 | <!-- -d Discard the remembered location of each NAME.
|
| 1253 | -l Display output in a format reusable as input.
|
| 1254 | -p PATH Inhibit path search, PATH is used as location for NAME.
|
| 1255 | -t Print the full path of one or more NAME.-->
|
| 1256 |
|
| 1257 | ### cmd/type
|
| 1258 |
|
| 1259 | type FLAG* NAME+
|
| 1260 |
|
| 1261 | Print the type of each NAME, if it were the first word of a command. Is it a
|
| 1262 | shell keyword, builtin command, shell function, alias, or executable file on
|
| 1263 | $PATH?
|
| 1264 |
|
| 1265 | Flags:
|
| 1266 |
|
| 1267 | -a Show all possible candidates, not just the first one
|
| 1268 | -f Don't search for shell functions
|
| 1269 | -P Only search for executable files
|
| 1270 | -t Print a single word: alias, builtin, file, function, or keyword
|
| 1271 |
|
| 1272 | Similar names: [type][]
|
| 1273 |
|
| 1274 | [type]: chap-index.html#type
|
| 1275 |
|
| 1276 | <!-- TODO:
|
| 1277 | - procs are counted as shell functions, should be their own thing
|
| 1278 | - Hay nodes ('hay define x') also live in the first word namespace, and should
|
| 1279 | be recognized
|
| 1280 | -->
|
| 1281 |
|
| 1282 | Modeled after the [bash `type`
|
| 1283 | builtin](https://www.gnu.org/software/bash/manual/bash.html#index-type).
|
| 1284 |
|
| 1285 | ## Word Lookup
|
| 1286 |
|
| 1287 | ### command
|
| 1288 |
|
| 1289 | command FLAG* CMD ARG*
|
| 1290 |
|
| 1291 | Look up CMD as a shell builtin or executable file, and execute it with the
|
| 1292 | given ARGs. That is, the lookup ignores shell functions named CMD.
|
| 1293 |
|
| 1294 | Flags:
|
| 1295 |
|
| 1296 | -v Instead of executing CMD, print a description of it.
|
| 1297 | Similar to the 'type' builtin.
|
| 1298 | <!-- -p Use a default value for PATH that is guaranteed to find all of the
|
| 1299 | standard utilities.
|
| 1300 | -V Print a more verbose description of CMD.-->
|
| 1301 |
|
| 1302 | ### builtin
|
| 1303 |
|
| 1304 | builtin CMD ARG*
|
| 1305 |
|
| 1306 | Look up CMD as a shell builtin, and execute it with the given ARGs. That is,
|
| 1307 | the lookup ignores shell functions and executables named CMD.
|
| 1308 |
|
| 1309 | ## Interactive
|
| 1310 |
|
| 1311 | ### alias
|
| 1312 |
|
| 1313 | alias NAME=CODE
|
| 1314 |
|
| 1315 | Make NAME a shortcut for executing CODE, e.g. `alias hi='echo hello'`.
|
| 1316 |
|
| 1317 | alias NAME
|
| 1318 |
|
| 1319 | Show the value of this alias.
|
| 1320 |
|
| 1321 | alias
|
| 1322 |
|
| 1323 | Show a list of all aliases.
|
| 1324 |
|
| 1325 | Tips:
|
| 1326 |
|
| 1327 | Prefer shell functions like:
|
| 1328 |
|
| 1329 | ls() {
|
| 1330 | command ls --color "$@"
|
| 1331 | }
|
| 1332 |
|
| 1333 | to aliases like:
|
| 1334 |
|
| 1335 | alias ls='ls --color'
|
| 1336 |
|
| 1337 | Functions are less likely to cause parsing problems.
|
| 1338 |
|
| 1339 | - Quoting like `\ls` or `'ls'` disables alias expansion
|
| 1340 | - To remove an existing alias, use [unalias](chap-builtin-cmd.html#unalias).
|
| 1341 |
|
| 1342 | ### unalias
|
| 1343 |
|
| 1344 | unalias NAME
|
| 1345 |
|
| 1346 | Remove the alias NAME.
|
| 1347 |
|
| 1348 | <!--Flag:
|
| 1349 |
|
| 1350 | -a Removes all existing aliases.-->
|
| 1351 |
|
| 1352 | ### history
|
| 1353 |
|
| 1354 | history FLAG*
|
| 1355 |
|
| 1356 | Display and manipulate the shell's history entries.
|
| 1357 |
|
| 1358 | history NUM
|
| 1359 |
|
| 1360 | Show the last NUM history entries.
|
| 1361 |
|
| 1362 | Flags:
|
| 1363 |
|
| 1364 | -c Clears the history.
|
| 1365 | -d POS Deletes the history entry at position POS.
|
| 1366 | <!-- -a
|
| 1367 | -n
|
| 1368 | -r
|
| 1369 | -w
|
| 1370 | -p
|
| 1371 | -s -->
|
| 1372 |
|
| 1373 |
|
| 1374 | ## Unsupported
|
| 1375 |
|
| 1376 | ### enable
|
| 1377 |
|
| 1378 | Bash has this, but OSH won't implement it.
|
| 1379 |
|