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| -rw-r--r-- | libbutl/process.mxx | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/libbutl/process.mxx b/libbutl/process.mxx index ab5e84f..0677525 100644 --- a/libbutl/process.mxx +++ b/libbutl/process.mxx @@ -191,6 +191,26 @@ LIBBUTL_MODEXPORT namespace butl bool normal () const; + // C/C++ don't apply constraints on program exit code other than it being + // of type int. + // + // POSIX specifies that only the least significant 8 bits shall be + // available from wait() and waitpid(); the full value shall be available + // from waitid() (read more at _Exit, _exit Open Group spec). + // + // While the Linux man page for waitid() doesn't mention any deviations + // from the standard, the FreeBSD implementation (as of version 11.0) only + // returns 8 bits like the other wait*() calls. + // + // Windows supports 32-bit exit codes. + // + // Note that in shells some exit values can have special meaning so using + // them can be a source of confusion. For bash values in the [126, 255] + // range are such a special ones (see Appendix E, "Exit Codes With Special + // Meanings" in the Advanced Bash-Scripting Guide). + // + // So [0, 125] appears to be the usable exit code range. + // code_type code () const; |