I want to exec a program and control it's arguments including arg0 and environment. Using C I could go for execve. Can I do this in POSIX shell?
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3Depending on the situation, you could make a symlink with the desired arg0 and exec that insteadmuru– muru2024-03-16 03:57:07 +00:00Commented Mar 16, 2024 at 3:57
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According to POSIX documentation of Special Builtin Utilities, the syntax for exec is
exec [command [argument...]]
Environment of the calling shell should be propagated to command so setting it prior to exec-ing like foo=bar exec cmd should just work. However, you might want to consider the Rationale paragraph.
Most historical implementations were not conformant in that: foo=bar exec cmd did not pass foo to cmd.
There is also no built-in way to fiddle argv[0].
a possible workaround could consist in symlinking some_name to command prior to exec some_name (full credit to muru)
Note that bash zsh and ksh do support an extended implementation of the exec command :
exec [-cl] [-a name] [command [arguments]]
which, thanks, to the -a option enables name to stand as argv[0]
with -a argv0 set the argv[0] string of the command executed
However, neither csh nor dash nor fish support that.
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A symlink won't always do the trick, because the path component may often be different from the intended argv[0], although the basename can be the same.jrw32982– jrw329822024-03-21 02:32:44 +00:00Commented Mar 21, 2024 at 2:32