Feed ARGV into one-liner

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

Replies are listed 'Best First'.
Re: Feed ARGV into one-liner by almut (Canon) on Jan 21, 2010 at 14:51 UTC
You can use a BEGIN block to operate on @ARGV (the `$v=shift` below, shifting off the first arg) before the implicit `while (<>) {}` loop (behind `-n`) takes effect treating the remaining arguments as file names. `$ perl -n -a -e 'BEGIN {$v=shift} if (($_ = "$F[1]\n") =~ /$v/) { prin +t }' Vet TEST.txt` [download]	[reply] [d/l] [select]
Re^2: Feed ARGV into one-liner by Saved (Beadle) on Jan 21, 2010 at 14:55 UTC
Thanx, that is great!	[reply]
Re: Feed ARGV into one-liner (the sane way :) by BrowserUk (Patriarch) on Jan 21, 2010 at 15:17 UTC
Another way. use perl's builtin argument parsing: `c:\test>perl -sane"print if $F[ 1 ] =~ /$T/" -- -T=vet test.txt b vet c f vet g` [download] Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. "I'd rather go naked than blow up my ass"	[reply] [d/l]
Re: Feed ARGV into one-liner by JavaFan (Canon) on Jan 21, 2010 at 17:02 UTC
Don't underestimate the power of command line switches: `perl -MB';$'F=shift -ane '$F[1]=~$F&&'print -- Vet TEST.txt` [download]	[reply] [d/l]
Re^2: Feed ARGV into one-liner by fod (Friar) on Jan 22, 2010 at 09:59 UTC
Can you explain this please? In particular what does `B';$'F=shift` do? It's melting my head.... thanks	[reply] [d/l]
Re^3: Feed ARGV into one-liner by ikegami (Patriarch) on Jan 22, 2010 at 10:25 UTC
Shell literal `-MB';$'F=shift` [download] produces the arg `-MB;$F=shift` [download] You're probably familiar with `-M`. It used to load a module. It does so by inserting `use MODULENAME;` [download] into the source. In this case, `MODULENAME` is `B;$F=shift`, so `use B;$F=shift;` [download] is inserted into the source. B is a core module. It's not being used at all by the program. The only purpose to load it is to execute `$F=shift;` before the `-n` loop with very few keystrokes. The following would also work; it's just not nearly as short: `'-MData::Dumper; $F=shift'` [download]	[reply] [d/l] [select]
Re^4: Feed ARGV into one-liner by fod (Friar) on Jan 22, 2010 at 11:06 UTC
Re: Feed ARGV into one-liner by Anonymous Monk on Jan 21, 2010 at 14:42 UTC
What do you call a question which answers itself? `perl -lane ' print $F[1] if $F[1] =~ $ARGV[0] '` [download]	[reply] [d/l]
Re^2: Feed ARGV into one-liner by Saved (Beadle) on Jan 21, 2010 at 14:51 UTC
But how do I give it the filename and the search value?	[reply]
Re^3: Feed ARGV into one-liner by Anonymous Monk on Jan 21, 2010 at 14:56 UTC
Whooops	[reply]
Re: Feed ARGV into one-liner by Krambambuli (Curate) on Jan 22, 2010 at 16:52 UTC
A bit OT to your direct question, but just as an idea: it's sometimes useful and easy to also use the shell as a helper. You could write a shell script vet.sh containing perl -ne 'print $_ if /'$1'/' $2 which invoked as ./vet.sh Vet Test.txt would also do what you asked for. As a side benefit, your oneliner is written down - just in the case you do not remember it well a week later when you need it again. :) Krambambuli ---	[reply]
Re^2: Feed ARGV into one-liner by Anonymous Monk on Jan 23, 2010 at 08:33 UTC
`cat >>oneliners.txt #frobnicates the fetzer valve perl -ne 'print $_ if /'$1'/' $2 ^D` [download]	[reply] [d/l]