Re^2: Using system(): converting error num to human readable message

Actually, i do know the diff between shell and Perl, I've been programming for a few yrs now.. ;-)
From what you two are saying, it sounds like it's impossible to do what I want anyway.
I tried your use of qx, but it failed thus:

@cmd_arr = ("someprog", "var");
$msg = qx/@cmd_arr 2>&1/;
if( $? )
{
    print "fail $?\n";
    print "$msg\n";
}

Result:
fail -1
Use of uninitialized value in concatenation (.) or string at ./err_cvt
+.pl line 17.
[download]

I read about the $? >> 8 in the Cookbook and I read the info about $! in a string context in perlvar http://perldoc.perl.org/perlvar.html#%24ERRNO, which is why I was trying to use those techniques.
I like to check rtn status' as much as possible and I've always hated the fact I can't get reliable sensible msgs from system(), so I thought I'd ask if there was a known solution.
Apparently not ... :-(

Cheers
Chris

PS any idea on Qn 3 ?

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Re^3: Using system(): converting error num to human readable message by naikonta (Curate) on Apr 18, 2007 at 05:18 UTC
I didn't mean to say that everytime you do `$msg = qx/prog 2>&1/` you always get error message in `$msg` because the error message totally depends on the program in question. In fact, your example shows that your execution on "someprog" doesn't say anything at all so `$msg` remains undefined, hence the warning message. Take a real progam as example, $ perl -wle '$msg = qx/ls -K 2>&1/; print "error: $?"; print $msg' error: 512 ls: invalid option -- K Try `ls --help' for more information. [download] If what you meant is that you want to capture the error on the fact that "someprog" command doesn't exist on the system, then you need to capture the error of the shell, not "someprog". Well, depending on your shell, `$ perl -wle '$msg = qx/bash -c ProgramNotExist 2>&1/; print "error: $? +"; print $msg' error: 32512 bash: ProgramNotExist: command not found` [download] Update: Rephrased the "In fact, ...." sentence. Open source softwares? Share and enjoy. Make profit from them if you can. Yet, share and enjoy!	[reply] [d/l] [select]

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Re^3: Using system(): converting error num to human readable message
by naikonta (Curate) on Apr 18, 2007 at 05:18 UTC

$msg = qx/prog 2>&1/

$msg

Take a real progam as example,

$ perl -wle '$msg = qx/ls -K 2>&1/; print "error: $?"; print $msg'
error: 512
ls: invalid option -- K
Try `ls --help' for more information.
[download]

If what you meant is that you want to capture the error on the fact that "someprog" command doesn't exist on the system, then you need to capture the error of the shell, not "someprog". Well, depending on your shell,

$ perl -wle '$msg = qx/bash -c ProgramNotExist 2>&1/; print "error: $?
+"; print $msg'
error: 32512
bash: ProgramNotExist: command not found
[download]

Update: Rephrased the "In fact, ...." sentence.

Open source softwares? Share and enjoy. Make profit from them if you can. Yet, share and enjoy!

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