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Full Discussion: Perl : Large amount of data put into an array
Top Forums Shell Programming and Scripting Perl : Large amount of data put into an array Post 302817455 by balajesuri on Wednesday 5th of June 2013 11:36:51 PM
Old 06-06-2013
Quote:
Originally Posted by MadeInGermany
You save the memory with
Code:
open (FH, "<file");
foreach $eachline (<FH>) {
   chomp $eachline;
   if ($eachline =~ /\b$ARGV[0]\b/) {
     print "$eachline\n";
   }
}

Actually, the program would be significantly quicker if you read the file using a while loop. Here's a small test to prove it:

Code:
[user@host ~]$ seq 1 1000000 > file
[user@host ~]$ time perl -e 'open I, "< file"; for (<I>) {$i++}; close I; END { print "$i\n" }'
1000000

real    0m0.563s
user    0m0.546s
sys     0m0.046s
[user@host ~]$ time perl -e 'open I, "< file"; while (<I>) {$i++}; close I; END { print "$i\n" }'
1000000

real    0m0.156s
user    0m0.171s
sys     0m0.015s
[user@host ~]$

Quote:
Originally Posted by MadeInGermany
and in this case even save the loop with
Code:
open (FH, "<file");
print grep (/\b$ARGV[0]\b/, <FH>);

IMHO, though visually this is not a loop, technically it is, as grep "evaluates the block or expression for each element of list"as per perldoc.
Last edited by balajesuri; 06-06-2013 at 12:46 AM..
 

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LEARN ABOUT OPENSOLARIS

gvfs-save

gvfs-save(1)							   User Commands						      gvfs-save(1)

NAME

       gvfs-save - save information to a file using the VFS system

SYNOPSIS

       gvfs-save [-b] [-c] [-a] [-p] [-v] [-e] URI

DESCRIPTION

       gvfs-save saves information to a file using the VFS system.

OPTIONS

       The following options are supported:

       -b	Create backup

       -c	Only create if not existing

       -a	Append to end of the file

       -p	When creating a file, restrict access to the current user only

       -v	Print etag that the end

       -e	The etag of the file being overwritting

EXAMPLES

       Example 1: Append a string to the end of a local file

       example% echo "hello" | gvfs-save file:///tmp/example

       Example 2: Append a file to a remote file storing a backup

       example% gvfs-cat file:///tmp/file | gvfs-save -b smb://server/dir/file

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/gvfs-save      Executable to save information to a file using the VFS system

ATTRIBUTES

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

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWgnome-gvfs		   |
       +-----------------------------+-----------------------------+
       |Interface stability	     |Volatile			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       gvfs-copy(1),  gvfs-cat(1), gvfs-less(1), gvfs-ls(1), gvfs-mkdir(1) gvfs-monitor-dir(1), gvfs-monitor-file(1), gvfs-mount(1), gvfs-move(1),
       gvfs-rename(1), gvfs-open(1), gvfs-rm(1), gvfs-info(1), gvfs-trash(1), gvfs-tree(1), attributes(5), environ(5)

NOTES

       Written by Alvaro Lopez Ortega, Sun Microsystems Inc., 2008.

SunOS 5.11							    25 Mar 2008 						      gvfs-save(1)
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