Capture error from one-liner

dirtdog has asked for the wisdom of the Perl Monks concerning the following question:

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Re: Capture error from one-liner by choroba (Cardinal) on Sep 19, 2014 at 16:41 UTC
This is not specific to korn shell. Perl with -p doesn't die if a file doesn't exist (cf. the behaviour of open). Unfortunately, autodie doesn't help here, so if you want it to die, you have to change the logic to something like `\| V perl -e 'for my $file (@ARGV) { open my $IN, "<", $file or die $!; whi +le (<$IN>) {s/AJZ/AZZ/g if /^AB/; print}}' input > output` [download] لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l]
Re^2: Capture error from one-liner by shmem (Chancellor) on Sep 19, 2014 at 16:54 UTC
Perl with -p doesn't die if a file doesn't exist Right you are; a workaround is `qwurx [shmem] ~ > perl -p -e 'BEGIN{$SIG{__WARN__}=sub{die@_}}' nonexi +stent Can't open nonexistent: No such file or directory. qwurx [shmem] ~ > echo $? 2` [download] perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'	[reply] [d/l]
Re^3: Capture error from one-liner by choroba (Cardinal) on Sep 19, 2014 at 16:56 UTC
Well, my one-liners are usually not warning-proof... لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply]
Re^2: Capture error from one-liner by LanX (Saint) on Sep 19, 2014 at 17:03 UTC
But wait the OP showed us an error displayed on the console! Maybe -i is producing it? Cheers Rolf _{(addicted to the Perl Programming Language and ☆☆☆☆ :)}	[reply]
Re^2: Capture error from one-liner by dirtdog (Monk) on Sep 19, 2014 at 16:48 UTC
thanks for the help I'll pipe the command to a log and grep for errors.	[reply]
Re: Capture error from one-liner by LanX (Saint) on Sep 19, 2014 at 16:14 UTC
> but what i have doesn't work. Unfortunately "doesn't work" doesn't work for us. :) Could you plz show us an error condition to reproduce your problem? Cheers Rolf _{(addicted to the Perl Programming Language and ☆☆☆☆ :)}	[reply]
Re^2: Capture error from one-liner by dirtdog (Monk) on Sep 19, 2014 at 16:26 UTC
Sure. Below is an example where the filename is not found. In this case i'd like to be able to capture an error and know that it failed. `perl -i.bak -pe 's/AJZ/AZZ/g if /^AB/' J_BB@ Can't open J_BB@: No such file or directory. echo $? 0` [download]	[reply] [d/l]
Re^3: Capture error from one-liner by LanX (Saint) on Sep 19, 2014 at 16:32 UTC
not an expert of korn-shell, but what you want is capturing STDERR. If there is no direct way to do it, but you could redirect STDERR to STDOUT and capture STDOUT. No idea if you need backticks° in ksh then!¹ (I would do the whole task completely within Perl not in ksh²) HTH (otherwise others will know =) Cheers Rolf _{(addicted to the Perl Programming Language and ☆☆☆☆ :)} updates °) ksh seems to support `$()` for backticks ¹) normally errors are piped into a file like here, bash can use backticks to capture STDOUT ²) should be mentioned that this is not a Perl question!	[reply] [d/l]
Re: Capture error from one-liner by Laurent_R (Canon) on Sep 19, 2014 at 17:53 UTC
A possible workaround redirecting STDERR: `$ perl -i.bak -pe 's/AJZ/AZZ/g if /^AB/' foobar 2> error.txt ~ $ cat error.txt Can't open foobar: No such file or directory.` [download] So you would just need to check if a non-empty error.txt file is created.	[reply] [d/l]
Re: Capture error from one-liner by Bloodnok (Vicar) on Sep 19, 2014 at 16:57 UTC
At it's simplest, could it not be ... `set -e [ -f $fname ] && [ -r $fname ] perl -i.bak -pe 's/AJZ/AZZ/g if /^AB/' $fname` [download] Just a thought ... A user level that continues to overstate my experience :-))	[reply] [d/l]

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