Grep in Perl - Searching through multiple files Post: 302628037

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Top Forums UNIX for Dummies Questions & Answers Grep in Perl - Searching through multiple files Post 302628037 by drl on Sunday 22nd of April 2012 11:35:44 PM

04-23-2012

Registered User

Hi.

Showing how system and grep perl functions work:

Code:

#!/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

producing:

Code:

% ./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

See perldoc perlop, searching for qx for more information.

Best wishes ... cheers, drl

( Edit 1: corrected error in perldoc advice. )

Last edited by drl; 04-23-2012 at 09:05 AM..

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LEARN ABOUT SUNOS

gnomevfs-cat

gnomevfs-cat(1) 						   User Commands						   gnomevfs-cat(1)

NAME

       gnomevfs-cat - print a file to standard output using the VFS system

SYNOPSIS

       gnomevfs-cat URI

DESCRIPTION

       gnomevfs-cat prints a file to standard output using the virtual file system to access the file via a URI.

OPERANDS

       The following operands are supported:

       URI	       Specifies the file location in standard URI format.

EXAMPLES

       Example 1: Cat a File From a Web Server

       example% gnomevfs-cat http://www.sun.com

       Example 2: Cat a Local File

       example% gnomevfs-cat file:///home/user/README.txt

ENVIRONMENT VARIABLES

       See environ(5) for descriptions of the following environment variables: NLSPATH.

EXIT STATUS

       The exit value 0 is returned regardless of success or failure.

FILES

       The following files are used by this application:

       /usr/bin/gnomevfs-cat   Executable to print a file to standard output using the VFS system

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWgnome-vfs		   |
       +-----------------------------+-----------------------------+
       |Interface stability	     |External			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       gnomevfs-copy(1), gnomevfs-info(1), gnomevfs-ls(1), gnomevfs-mkdir(1)

NOTES

       Written by Stephen Browne, Sun Microsystems Inc., 2004.

SunOS 5.10							    6 Sep 2004							   gnomevfs-cat(1)

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