Thank you Peter; that does the trick.
If the backtick command works (like `pwd`;) you get
$? = 0
$! = No such file or directory
But if you do e.g.
touch wibble
chmod -r wibble
then in Perl
`wibble` ;
you get
$? = 256
$! = Permission denied
I.e. when $? is non-zero $! describes what went wrong with the backtick
command, otherwise it's irrelevant. I guess when the backtick works Perl has
internally done some system call that gets $! set to "No such file.." (I got
this on 3 different platforms: NCR (SVR4), Solaris and Windows.)
Thanks again - I'd been struggling with this for ages. (And thanks to the
others who've replied as I've been typing this!)
Ron
-----Original Message-----
From: Peter Cornelius [mailto:[EMAIL PROTECTED]]
Sent: 23 May 2001 19:14
To: 'Mitchell, Ronald'; '[EMAIL PROTECTED]'
Subject: RE: $! after using backticks
>I want to check that a backtick command has executed OK. I thought I could
>do that by looking at the $! variable.
Check $?
This is Child exit status which is what you get when you spawn another
process with back ticks.
The $! is the ERRNO (or Error string depending on context) for the last
system call.
Hope this helps,
Peter C.
