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

456 lines, 326 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-ysh-cmd.html#var)
80 keyword?
81- Did you mean to use the [setglobal](ref/chap-ysh-cmd.html#setglobal)
82 keyword?
83
84Related help topics:
85
86- [setvar](ref/chap-ysh-cmd.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 && c) {
183 echo no
184 }
185
186 # Command mode
187 if not test --dir a or test --dir b and test --dir c {
188 echo no
189 }
190
191Correct:
192
193 # Expression mode
194 if (not a or b and c) {
195 echo yes
196 }
197
198 # Command mode
199 if ! test --dir a || test --dir b && test --dir c {
200 echo yes
201 }
202
203In general, code within parentheses `()` is parsed as Python-like expressions
204-- referred to as [expression mode](command-vs-expression-mode.html). The
205standard boolean operators are written as `a and b`, `a or b` and `not a`.
206
207This differs from [command mode](command-vs-expression-mode.html) which uses
208shell-like `||` for "OR", `&&` for "AND" and `!` for "NOT".
209
210### OILS-ERR-16
211
212```
213 for x in (1 .. 5) {
214 ^~
215[ -c flag ]:1: Use ..< for half-open range, or ..= for closed range (OILS-ERR-16)
216```
217
218There are two ways to construct a [Range](ref/chap-expr-lang#range). The `..<`
219operator is for half-open ranges and the `..=` operator is for closed ranges:
220
221 for i in (0 ..< 3) {
222 echo $i
223 }
224 => 0
225 => 1
226 => 2
227
228 for i in (0 ..= 3) {
229 echo $i
230 }
231 => 0
232 => 1
233 => 2
234 => 3
235
236## Runtime Errors - Traditional Shell
237
238These errors may occur in shells like [bash]($xref) and [zsh]($xref).
239
240They're numbered starting from `100`. (If we have more than 90 parse errors,
241we can start a new section, like `300`.)
242
243### OILS-ERR-100
244
245<!--
246Generated with:
247test/runtime-errors.sh test-command-not-found
248-->
249
250```
251 findz
252 ^~~~~
253[ -c flag ]:1: 'findz' not found (OILS-ERR-100)
254```
255
256- Did you misspell a command name?
257- Did you misspell a shell function or a YSH `proc`?
258- Is the file in your `$PATH`? The `PATH` variable is a colon-separated list
259 of directories, where executable files may live.
260- Is `findz` file executable bit set? (`chmod +x`)
261
262### OILS-ERR-101
263
264<!--
265Generated with:
266test/runtime-errors.sh test-assoc-array
267-->
268
269Let's look at **three** instances of this error.
270
271```
272 declare -A assoc; assoc[x]=1
273 ^~~~~~
274[ -c flag ]:1: fatal: Assoc array keys must be strings: $x 'x' "$x" etc. (OILS-ERR-101)
275```
276
277- Is `x` a string? Then add quotes: `assoc['x']=1`
278- Is `x` a variable? Then write: `assoc[$x]=1`
279
280---
281
282Same idea here:
283
284```
285 declare -A assoc; echo ${assoc[x]}
286 ^
287[ -c flag ]:1: fatal: Assoc array keys must be strings: $x 'x' "$x" etc. (OILS-ERR-101)
288```
289
290- Is `x` a string? Then add quotes: `${assoc['x']}`
291- Is `x` a variable? Then write: `${assoc[$x]}`
292
293---
294
295The third example is **tricky** because `unset` takes a **string**. There's an
296extra level of parsing, which:
297
298- Implies an extra level of quoting
299- Causes OSH to display the following **nested** error message
300
301```
302 assoc[k]
303 ^
304[ dynamic LHS word at line 1 of [ -c flag ] ]:1
305
306 declare -A assoc; key=k; unset "assoc[$key]"
307 ^
308[ -c flag ]:1: fatal: Assoc array keys must be strings: $x 'x' "$x" etc. (OILS-ERR-101)
309```
310
311To fix it, consider using **single quotes**:
312
313 unset 'assoc[$key]'
314
315---
316
317- This is the error in [Parsing Bash is
318 Undecidable](https://www.oilshell.org/blog/2016/10/20.html) (2016)
319- Also mentioned in [Known Differences](known-differences.html)
320
321
322## Runtime Errors - Oils and YSH
323
324These errors don't occur in shells like [bash]($xref) and [zsh]($xref).
325
326They may involve Python-like **expressions** and **typed data**.
327
328They're numbered starting from `200`.
329
330### OILS-ERR-200
331
332<!--
333Generated with:
334test/runtime-errors.sh test-external_cmd_typed_args
335-->
336
337```
338 cat ("myfile")
339 ^
340[ -c flag ]:1: fatal: 'cat' appears to be external. External commands don't accept typed args (OILS-ERR-200)
341```
342
343- Builtin commands and user-defined procs may accept [typed
344 args](ref/chap-cmd-lang.html#typed-arg), but external commands never do.
345- Did you misspell a [YSH proc](ref/chap-cmd-lang.html#proc-def)? If a name is
346 not found, YSH assumes it's an external command.
347- Did you forget to source a file that contains the proc or shell function you
348 wanted to run?
349
350### OILS-ERR-201
351
352<!--
353Generated with:
354test/runtime-errors.sh test-arith_ops_str
355-->
356
357```
358 = "age: " + "100"
359 ^
360[ -c flag ]:1: fatal: Binary operator expected numbers, got Str and Str (OILS-ERR-201)
361
362 = 100 + myvar
363 ^
364[ -c flag ]:2: fatal: Binary operator expected numbers, got Int and Str (OILS-ERR-201)
365```
366
367- Did you mean to use `++` to concatenate strings/lists?
368- The arithmetic operators [can coerce string operands to
369 numbers](ref/chap-expr-lang.html#ysh-arith). However, if you are operating on
370 user provided input, it may be a better idea to first parse that input with
371 [`int()`](ref/chap-builtin-func.html#int) or
372 [`float()`](ref/chap-builtin-func.html#float).
373
374### OILS-ERR-202
375
376<!--
377Generated with:
378test/ysh-runtime-errors.sh test-float-equality
379-->
380
381```
382 pp (42.0 === x)
383 ^~~
384[ -c flag ]:3: fatal: Equality isn't defined on Float values (OILS-ERR-202)
385```
386
387Floating point numbers shouldn't be tested for equality. Alternatives:
388
389 = abs(42.0 - x) < 0.1
390 = floatEquals(42.0, x)
391
392### OILS-ERR-203
393
394<!--
395Generated with:
396test/ysh-runtime-errors.sh test-cannot-stringify-list
397-->
398
399```
400 var mylist = [1,2,3]; write $[mylist]
401 ^~
402[ -c flag ]:1: fatal: Expr sub got a List, which can't be stringified (OILS-ERR-203)
403```
404
405- Did you mean to use `@mylist` instead of `$mylist`?
406- Did you mean to use `@[myfunc()]` instead of `$[myfunc()]`?
407- Did you mean `$[join(mylist)]`?
408
409Or:
410
411- Do you have an element that can't be stringified in a list, like `['good',
412 {bad: true}]`?
413
414
415<!-- TODO -->
416
417## Runtime Errors: `strict:all`
418
419### OILS-ERR-300
420
421```
422 if ! ls | wc -l; then echo failed; fi
423 ^
424[ -c flag ]:1: fatal: Command conditionals should only have one status, not Pipeline (strict_errexit, OILS-ERR-300)
425```
426
427Compound commands can't be used as conditionals because it's ambiguous.
428
429It confuses true/false with pass/fail. What if part of the pipeline fails?
430What if `ls` doesn't exist?
431
432This YSH idiom is more explicit:
433
434 try {
435 ls | wc -l
436 }
437 if (_error.code !== 0) {
438 echo failed
439 }
440
441## Appendix
442
443### Kinds of Errors from Oils
444
445- Runtime errors (status 1) - the shell tried to do something, but failed.
446 - Example: `echo hi > /does/not/exist`
447- Parse errors and builtin usage errors (status 2) - input rejected, so the
448 shell didn't try to do anything.
449- Uncaught I/O errors (status 2)
450- Expression errors (status 3)
451- User errors from the `error` builtin (status 10 is default)
452
453### Contributors
454
455(If you updated this doc, feel free to add your name to the end of this list.)
456