UNIX for Dummies Questions & Answers

grep -l 'pattern' *

	my $dir = "/cygdrive/c/TEMP; 
	opendir (my $dh, $dir) or die "Can't open $dir: $!";
		my @allFiles = grep { -f "$dir/$_" } readdir($dh);
	closedir $dh;
	
	my @legFiles = grep {/pattern/} @allFiles;
	foreach (@legFiles) {print "$_\n"};

       grep BLOCK LIST
       grep EXPR,LIST
               This is similar in spirit to, but not the same as, grep(1) and
               its relatives.  In particular, it is not limited to using
               regular expressions.

               Evaluates the BLOCK or EXPR for each element of LIST (locally
               setting $_ to each element) and returns the list value
               consisting of those elements for which the expression evaluated
               to true.  In scalar context, returns the number of times the
               expression was true.
-- excerpt from perldoc -f grep, q.v.

$ perl -ne 'if ( m/pattern/ ) { printf qq[%s\n], $ARGV; close ARGV; }' *

#!/usr/bin/env bash

# @(#) s2	Demonstrate command (not function) _grep_ from perl.

pe() { for _i;do printf "%s" "$_i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
db() { ( printf " db, ";for _i;do printf "%s" "$_i";done;printf "\n" ) >&2 ; }
db() { : ; }
C=$HOME/bin/context && [ -f $C ] && $C perl

pl " Files data{1,2,4}.txt have this content:"
cat data1.txt

pl " File data3.txt:"
cat data3.txt

pl " perl script p1:"
cat p1

pl " Results:"
./p1

exit 0

% ./s2

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 2.6.26-2-amd64, x86_64
Distribution        : Debian GNU/Linux 5.0.8 (lenny) 
bash GNU bash 3.2.39
perl 5.10.0

-----
 Files data{1,2,4} have this content:
Now is the time
for all good men
to come to the aid
of their country.

-----
 File data3.txt:
Nothing to see here. Move along. Move along.

-----
 perl script p1:
#!/usr/bin/env perl

# @(#) p1	Demonstrate feature (minimal).

use strict;
use warnings;

my(@a);

print "\n";
print " Output directly from system to STDOUT:\n";
system('grep -l time *.txt');

print "\n";
@a = qx/grep -l time *.txt/;
print " List from qx:\n ", join(" ",@a), "\n";

exit 0;

-----
 Results:

 Output directly from system to STDOUT:
data1.txt
data2.txt
data4.txt

 List from qx:
 data1.txt
 data2.txt
 data4.txt