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Model situation:
complex bash script has failed with some non-obvious exit code while
the subsequent runs are as expected (i.e., intermittent error or
something of that kind)
Solution #1: quick web search
Solution #2: study all the functions and program invocations on all/guessed
code paths wrt. their return codes (not always properly
documented!) + add some bash runtime considerations
Solution #3: grep this document and pray it will help you :)
2
* bash:*
- incorrect use of builtins
$ [
bash: [: missing `]'
126
* bash
- command found but not executable
$ /etc
bash: /etc: Is a directory
127
* general
- cannot dynamically link in run-time (TODO: who is responsible here, exactly?):
$ ./testfoo
./testfoo: error while loading shared libraries: libgetfoo.so: cannot open shared object file: No such file or directory
* bash
- unknown function/command
$ foo
bash: foo: command not found
* bash:wait
- waiting for nonexistent process/job
$ /bin/true & { sleep 1; wait $(($! - 1));}
bash: wait: pid 2864 is not a child of this shell
254
* bash
- when cannot fork so as to perform the command due to hitting number
of user processes limit, it will (IIUIC, first it will keep looping
over emitting "fork: retry: No child processes" and "fork: Resource
temporarily unavailable" messages, until it is eventually able to do
a fork to get outside of this loop, and then it will...) will
yield such exit status:
$ ulimit -u $(($(ps --no-headers -mu $(id -u) | wc -l) + 1))
$ sleep 1 & sleep 1
bash: fork: retry: No child processes
bash: fork: retry: No child processes
bash: fork: retry: No child processes
bash: fork: retry: No child processes
bash: fork: Resource temporarily unavailable
[...]
bash: fork: retry: No child processes
bash: fork: retry: No child processes
bash: fork: retry: No child processes
bash: fork: retry: No child processes
- see also [1]
- bash code perspective:
jobs.c:
last_command_exit_value = EX_NOEXEC;
/** exit_value = EX_NOEXEC = 126 **/
throw_to_top_level (); /* Reset signals, etc. */
/** exit_value = 126 | 128 = 254 **/
[1] http://unix.stackexchange.com/questions/19113/fork-negative-return-value/19119#19119
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