08-exit-codes.txt: trying to systematically map common exit codes

Especially aiming bash.

Signed-off-by: Jan Pokorný <jpokorny@redhat.com>

1 files changed, 62 insertions, 0 deletions

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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]
+
+
+[1] http://unix.stackexchange.com/questions/19113/fork-negative-return-value/19119#19119