How can I get the CPU time for a perl system call?

Question

I have a perl script that calls external executables using system(). I would like to measure the CPU seconds taken by these external programs. Ideally, I would like

Answer 1

$ time ( ls ) 2> er ## works
$ perl -e 'system("time (ls)")'
sh: 1: Syntax error: word unexpected (expecting ")")

The problem is that in first case, your shell is probably /bin/bash whereas in second case it is /bin/sh. If you want to run your command with another shell, you could use system LIST form:

system("/bin/bash", "-c", "time(ls)")

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Note 1: There's PERL5SHELL environmnet value, but that seems to take effect only on Win32.

Note 2: If you want to measure CPU time of child process, you could use Unix::Getrusage or BSD::Resource modules.