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

374 lines, 264 significant
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## Runtime Errors - Traditional Shell
178
179These errors may occur in shells like [bash]($xref) and [zsh]($xref).
180
181They're numbered starting from `100`. (If we have more than 90 parse errors,
182we can start a new section, like `300`.)
183
184### OILS-ERR-100
185
186<!--
187Generated with:
188test/runtime-errors.sh test-command-not-found
189-->
190
191```
192 findz
193 ^~~~~
194[ -c flag ]:1: 'findz' not found (OILS-ERR-100)
195```
196
197- Did you misspell a command name?
198- Did you misspell a shell function or a YSH `proc`?
199- Is the file in your `$PATH`? The `PATH` variable is a colon-separated list
200 of directories, where executable files may live.
201- Is `findz` file executable bit set? (`chmod +x`)
202
203### OILS-ERR-101
204
205<!--
206Generated with:
207test/runtime-errors.sh test-assoc-array
208-->
209
210Let's look at **three** instances of this error.
211
212```
213 declare -A assoc; assoc[x]=1
214 ^~~~~~
215[ -c flag ]:1: fatal: Assoc array keys must be strings: $x 'x' "$x" etc. (OILS-ERR-101)
216```
217
218- Is `x` a string? Then add quotes: `assoc['x']=1`
219- Is `x` a variable? Then write: `assoc[$x]=1`
220
221---
222
223Same idea here:
224
225```
226 declare -A assoc; echo ${assoc[x]}
227 ^
228[ -c flag ]:1: fatal: Assoc array keys must be strings: $x 'x' "$x" etc. (OILS-ERR-101)
229```
230
231- Is `x` a string? Then add quotes: `${assoc['x']}`
232- Is `x` a variable? Then write: `${assoc[$x]}`
233
234---
235
236The third example is **tricky** because `unset` takes a **string**. There's an
237extra level of parsing, which:
238
239- Implies an extra level of quoting
240- Causes OSH to display the following **nested** error message
241
242```
243 assoc[k]
244 ^
245[ dynamic LHS word at line 1 of [ -c flag ] ]:1
246
247 declare -A assoc; key=k; unset "assoc[$key]"
248 ^
249[ -c flag ]:1: fatal: Assoc array keys must be strings: $x 'x' "$x" etc. (OILS-ERR-101)
250```
251
252To fix it, consider using **single quotes**:
253
254 unset 'assoc[$key]'
255
256---
257
258- This is the error in [Parsing Bash is
259 Undecidable](https://www.oilshell.org/blog/2016/10/20.html) (2016)
260- Also mentioned in [Known Differences](known-differences.html)
261
262
263## Runtime Errors - Oils and YSH
264
265These errors don't occur in shells like [bash]($xref) and [zsh]($xref).
266
267They may involve Python-like **expressions** and **typed data**.
268
269They're numbered starting from `200`.
270
271### OILS-ERR-200
272
273<!--
274Generated with:
275test/runtime-errors.sh test-external_cmd_typed_args
276-->
277
278```
279 cat ("myfile")
280 ^
281[ -c flag ]:1: fatal: 'cat' appears to be external. External commands don't accept typed args (OILS-ERR-200)
282```
283
284- Builtin commands and user-defined procs may accept [typed
285 args](ref/chap-cmd-lang.html#typed-arg), but external commands never do.
286- Did you misspell a [YSH proc](ref/chap-cmd-lang.html#proc-def)? If a name is
287 not found, YSH assumes it's an external command.
288- Did you forget to source a file that contains the proc or shell function you
289 wanted to run?
290
291### OILS-ERR-201
292
293<!--
294Generated with:
295test/runtime-errors.sh test-arith_ops_str
296-->
297
298```
299 = "age: " + "100"
300 ^
301[ -c flag ]:1: fatal: Binary operator expected numbers, got Str and Str (OILS-ERR-201)
302
303 = 100 + myvar
304 ^
305[ -c flag ]:2: fatal: Binary operator expected numbers, got Int and Str (OILS-ERR-201)
306```
307
308- Did you mean to use `++` to concatenate strings/lists?
309- The arithmetic operators [can coerce string operands to
310 numbers](ref/chap-expr-lang.html#ysh-arith). However, if you are operating on
311 user provided input, it may be a better idea to first parse that input with
312 [`int()`](ref/chap-builtin-func.html#int) or
313 [`float()`](ref/chap-builtin-func.html#float).
314
315### OILS-ERR-202
316
317<!--
318Generated with:
319test/ysh-runtime-errors.sh test-float-equality
320-->
321
322```
323 pp (42.0 === x)
324 ^~~
325[ -c flag ]:3: fatal: Equality isn't defined on Float values (OILS-ERR-202)
326```
327
328Floating point numbers shouldn't be tested for equality. Alternatives:
329
330 = abs(42.0 - x) < 0.1
331 = floatEquals(42.0, x)
332
333### OILS-ERR-203
334
335<!--
336Generated with:
337test/ysh-runtime-errors.sh test-cannot-stringify-list
338-->
339
340```
341 var mylist = [1,2,3]; write $[mylist]
342 ^~
343[ -c flag ]:1: fatal: Expr sub got a List, which can't be stringified (OILS-ERR-203)
344```
345
346- Did you mean to use `@mylist` instead of `$mylist`?
347- Did you mean to use `@[myfunc()]` instead of `$[myfunc()]`?
348- Did you mean `$[join(mylist)]`?
349
350Or:
351
352- Do you have an element that can't be stringified in a list, like `['good',
353 {bad: true}]`?
354
355
356<!-- TODO -->
357
358
359## Appendix
360
361### Kinds of Errors from Oils
362
363- Runtime errors (status 1) - the shell tried to do something, but failed.
364 - Example: `echo hi > /does/not/exist`
365- Parse errors and builtin usage errors (status 2) - input rejected, so the
366 shell didn't try to do anything.
367- Uncaught I/O errors (status 2)
368- Expression errors (status 3)
369- User errors from the `error` builtin (status 10 is default)
370
371### Contributors
372
373(If you updated this doc, feel free to add your name to the end of this list.)
374