OILS / doc / error-catalog.md View on Github | oilshell.org

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1---
2default_highlighter: oils-sh
3---
4
5Oils Error Catalog, With Hints
6==================
7
8This doc lists errors from Oils (both [OSH]($xref) and [YSH]($xref)), with
9hints to help you fix them.
10
11Each error is associated with a code like `OILS-ERR-42`, a string that search
12engines should find.
13
14<!--
15Later, we could have a URL shortener, like https://oils.err/42
16-->
17
18<div id="toc">
19</div>
20
21## How to Contribute
22
23If you see an error that you don't understand:
24
251. Ask a question on `#oil-help` on [Zulip]($xref:zulip). What's the problem,
26 and what's the solution?
271. Then `grep` the source code for the confusing error message. Tag it with a
28 string like `OILS-ERR-43`, picking a new number according to the conventions
29 below.
301. Add a tagged section below, with hints and explanations.
31 - Quote the error message. You may want copy and paste from the output of
32 `test/{parse,runtime,ysh-parse,ysh-runtime}-errors.sh`. Add an HTML
33 comment `<!-- -->` about that.
34 - Link to relevant sections in the [**Oils Reference**](ref/index.html).
351. Optionally, add your name to the acknowledgements list at the end of this
36 doc.
37
38Note that error messages are **hard** to write, because a single error could
39result from many different user **intentions**!
40
41### To Preview this Doc
42
43Right now I use this command:
44
45 build/doc.sh split-and-render doc/error-catalog.md
46
47Then paste this into your browser:
48
49 file:///home/andy/git/oilshell/oil/_release/VERSION/doc/error-catalog.html
50
51(Replace with your home dir)
52
53## Parse Errors - Rejected Input
54
55Roughly speaking, a parse error means that text input was **rejected**, so the
56shell didn't try to do anything.
57
58Examples:
59
60 echo ) # Shell syntax error
61
62 type -z # -z flag not accepted
63
64These error codes start at `10`.
65
66### OILS-ERR-10
67
68<!--
69Generated with:
70test/ysh-parse-errors.sh test-func-var-checker
71-->
72
73```
74 setvar x = true
75 ^
76[ -c flag ]:3: setvar couldn't find matching 'var x' (OILS-ERR-10)
77```
78
79- Did you forget to declare the name with the [var](ref/chap-cmd-lang.html#var)
80 keyword?
81- Did you mean to use the [setglobal](ref/chap-cmd-lang.html#setglobal)
82 keyword?
83
84Related help topics:
85
86- [setvar](ref/chap-cmd-lang.html#setvar)
87
88### OILS-ERR-11
89
90<!--
91Generated with:
92test/ysh-parse-errors.sh ysh_c_strings (this may move)
93-->
94
95```
96 echo $'\z'
97 ^
98[ -c flag ]:1: Invalid char escape in C-style string literal (OILS-ERR-11)
99```
100
101- Did you mean `$'\\z'`? Backslashes must be escaped in `$''` and `u''` and
102 `b''` strings.
103- Did you mean something like `$'\n'`? Only valid escapes are accepted in YSH.
104
105Related help topics:
106
107- [osh-string](ref/chap-word-lang.html#osh-string) (word language)
108- [ysh-string](ref/chap-expr-lang.html#ysh-string) (expression language)
109
110### OILS-ERR-12
111
112<!--
113Generated with:
114test/ysh-parse-errors.sh ysh_dq_strings (this may move)
115-->
116
117```
118 echo "\z"
119 ^
120[ -c flag ]:1: Invalid char escape in double quoted string (OILS-ERR-12)
121```
122
123- Did you mean `"\\z"`? Backslashes must be escaped in double-quoted strings.
124- Did you mean something like `"\$"`? Only valid escapes are accepted in YSH.
125- Did you to use single quotes, like `u'\n'` rather than `u"\n"`?
126
127Related help topics:
128
129- [osh-string](ref/chap-word-lang.html#osh-string) (word language)
130- [ysh-string](ref/chap-expr-lang.html#ysh-string) (expression language)
131
132### OILS-ERR-13
133
134<!--
135Generated with:
136test/ysh-parse-errors.sh ysh_bare_words (this may move)
137-->
138
139```
140 echo \z
141 ^~
142[ -c flag ]:1: Invalid char escape in unquoted word (OILS-ERR-13)
143```
144
145- Did you mean `\\z`? Backslashes must be escaped in unquoted words.
146- Did you mean something like `\$`? Only valid escapes are accepted in YSH.
147
148### OILS-ERR-14
149
150<!--
151Generated with:
152test/ysh-parse-errors.sh test-parse-dparen
153-->
154
155```
156 if ((1 > 0 && 43 > 42)); then echo yes; fi
157 ^~
158[ -c flag ]:1: Bash (( not allowed in YSH (parse_dparen, see OILS-ERR-14 for wart)
159```
160
161Two likely causes:
162
163- Do you need to rewrite bash arithmetic as YSH arithmetic (which is
164 Python-like)?
165- Do you need to work around an [unfortunate wart](warts.html#two-left-parens-should-be-separated-by-space) in YSH?
166
167Examples:
168
169 if (1 > 0 and 43 > 42) { # YSH-style
170 echo yes
171 }
172
173 if ( (x + 1) < n) { # space between ( ( avoids ((
174 echo yes
175 }
176
177### OILS-ERR-15
178
179Incorrect:
180
181 # Expression mode
182 if (a || b) {
183 echo yes
184 }
185
186 # Command mode
187 if test --dir a or test --dir b { ... }
188
189Correct:
190
191 # Expression mode
192 if (a or b) {
193 echo yes
194 }
195
196 # Command mode
197 if test --dir a || test --dir b { ... }
198
199In general, code within parentheses `()` is parsed as Python-like expressions
200-- referred to as [expression mode](command-vs-expression-mode.html). The
201standard boolean operators are written as `a and b`, `a or b` and `not a`.
202
203This differs from [command mode](command-vs-expression-mode.html) which uses
204`||` for "OR", `&&` for "AND" and `!` for "NOT".
205
206## Runtime Errors - Traditional Shell
207
208These errors may occur in shells like [bash]($xref) and [zsh]($xref).
209
210They're numbered starting from `100`. (If we have more than 90 parse errors,
211we can start a new section, like `300`.)
212
213### OILS-ERR-100
214
215<!--
216Generated with:
217test/runtime-errors.sh test-command-not-found
218-->
219
220```
221 findz
222 ^~~~~
223[ -c flag ]:1: 'findz' not found (OILS-ERR-100)
224```
225
226- Did you misspell a command name?
227- Did you misspell a shell function or a YSH `proc`?
228- Is the file in your `$PATH`? The `PATH` variable is a colon-separated list
229 of directories, where executable files may live.
230- Is `findz` file executable bit set? (`chmod +x`)
231
232### OILS-ERR-101
233
234<!--
235Generated with:
236test/runtime-errors.sh test-assoc-array
237-->
238
239Let's look at **three** instances of this error.
240
241```
242 declare -A assoc; assoc[x]=1
243 ^~~~~~
244[ -c flag ]:1: fatal: Assoc array keys must be strings: $x 'x' "$x" etc. (OILS-ERR-101)
245```
246
247- Is `x` a string? Then add quotes: `assoc['x']=1`
248- Is `x` a variable? Then write: `assoc[$x]=1`
249
250---
251
252Same idea here:
253
254```
255 declare -A assoc; echo ${assoc[x]}
256 ^
257[ -c flag ]:1: fatal: Assoc array keys must be strings: $x 'x' "$x" etc. (OILS-ERR-101)
258```
259
260- Is `x` a string? Then add quotes: `${assoc['x']}`
261- Is `x` a variable? Then write: `${assoc[$x]}`
262
263---
264
265The third example is **tricky** because `unset` takes a **string**. There's an
266extra level of parsing, which:
267
268- Implies an extra level of quoting
269- Causes OSH to display the following **nested** error message
270
271```
272 assoc[k]
273 ^
274[ dynamic LHS word at line 1 of [ -c flag ] ]:1
275
276 declare -A assoc; key=k; unset "assoc[$key]"
277 ^
278[ -c flag ]:1: fatal: Assoc array keys must be strings: $x 'x' "$x" etc. (OILS-ERR-101)
279```
280
281To fix it, consider using **single quotes**:
282
283 unset 'assoc[$key]'
284
285---
286
287- This is the error in [Parsing Bash is
288 Undecidable](https://www.oilshell.org/blog/2016/10/20.html) (2016)
289- Also mentioned in [Known Differences](known-differences.html)
290
291
292## Runtime Errors - Oils and YSH
293
294These errors don't occur in shells like [bash]($xref) and [zsh]($xref).
295
296They may involve Python-like **expressions** and **typed data**.
297
298They're numbered starting from `200`.
299
300### OILS-ERR-200
301
302<!--
303Generated with:
304test/runtime-errors.sh test-external_cmd_typed_args
305-->
306
307```
308 cat ("myfile")
309 ^
310[ -c flag ]:1: fatal: 'cat' appears to be external. External commands don't accept typed args (OILS-ERR-200)
311```
312
313- Builtin commands and user-defined procs may accept [typed
314 args](ref/chap-cmd-lang.html#typed-arg), but external commands never do.
315- Did you misspell a [YSH proc](ref/chap-cmd-lang.html#proc-def)? If a name is
316 not found, YSH assumes it's an external command.
317- Did you forget to source a file that contains the proc or shell function you
318 wanted to run?
319
320### OILS-ERR-201
321
322<!--
323Generated with:
324test/runtime-errors.sh test-arith_ops_str
325-->
326
327```
328 = "age: " + "100"
329 ^
330[ -c flag ]:1: fatal: Binary operator expected numbers, got Str and Str (OILS-ERR-201)
331
332 = 100 + myvar
333 ^
334[ -c flag ]:2: fatal: Binary operator expected numbers, got Int and Str (OILS-ERR-201)
335```
336
337- Did you mean to use `++` to concatenate strings/lists?
338- The arithmetic operators [can coerce string operands to
339 numbers](ref/chap-expr-lang.html#ysh-arith). However, if you are operating on
340 user provided input, it may be a better idea to first parse that input with
341 [`int()`](ref/chap-builtin-func.html#int) or
342 [`float()`](ref/chap-builtin-func.html#float).
343
344### OILS-ERR-202
345
346<!--
347Generated with:
348test/ysh-runtime-errors.sh test-float-equality
349-->
350
351```
352 pp (42.0 === x)
353 ^~~
354[ -c flag ]:3: fatal: Equality isn't defined on Float values (OILS-ERR-202)
355```
356
357Floating point numbers shouldn't be tested for equality. Alternatives:
358
359 = abs(42.0 - x) < 0.1
360 = floatEquals(42.0, x)
361
362### OILS-ERR-203
363
364<!--
365Generated with:
366test/ysh-runtime-errors.sh test-cannot-stringify-list
367-->
368
369```
370 var mylist = [1,2,3]; write $[mylist]
371 ^~
372[ -c flag ]:1: fatal: Expr sub got a List, which can't be stringified (OILS-ERR-203)
373```
374
375- Did you mean to use `@mylist` instead of `$mylist`?
376- Did you mean to use `@[myfunc()]` instead of `$[myfunc()]`?
377- Did you mean `$[join(mylist)]`?
378
379Or:
380
381- Do you have an element that can't be stringified in a list, like `['good',
382 {bad: true}]`?
383
384
385<!-- TODO -->
386
387
388## Appendix
389
390### Kinds of Errors from Oils
391
392- Runtime errors (status 1) - the shell tried to do something, but failed.
393 - Example: `echo hi > /does/not/exist`
394- Parse errors and builtin usage errors (status 2) - input rejected, so the
395 shell didn't try to do anything.
396- Uncaught I/O errors (status 2)
397- Expression errors (status 3)
398- User errors from the `error` builtin (status 10 is default)
399
400### Contributors
401
402(If you updated this doc, feel free to add your name to the end of this list.)
403