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Top Forums Shell Programming and Scripting Perl - Extract first column from file Post 302923103 by Neethu on Thursday 30th of October 2014 10:41:05 AM
Old 10-30-2014
Perl - Extract first column from file

Hi,

I want to extract first column from a file and redirect the output to another file in perl.

I am able to do this from command line by executing below commands.
Code:
perl -anle 'print $F[0]' Input.dat > Output.dat
perl -ne '@F = split("\t", $_); print "$F[0]\n";' Input.dat > Output.dat
perl -anE 'say "@F[0,1]"' Input.dat > Output.dat

But when I add this in perl script it is not working.
Code:
	$cmd = "perl -anle 'print $F[0]' ".$inFile." > ".$outFile;
	system($cmd);
	if ($? != 0)
	{
		errorLog("Could not create file ".$inFile);
	}


Regards
Neethu
 

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TRACE-CMD-HIST(1)														 TRACE-CMD-HIST(1)

NAME
trace-cmd-hist - show histogram of events in trace.dat file SYNOPSIS
trace-cmd hist [OPTIONS][input-file] DESCRIPTION
The trace-cmd(1) hist displays a histogram form from the trace.dat file. Instead of showing the events as they were ordered, it creates a histogram that can be displayed per task or for all tasks where the most common events appear first. It uses the function tracer and call stacks that it finds to try to put together a call graph of the events. OPTIONS
-i input-file By default, trace-cmd hist will read the file trace.dat. But the -i option open up the given input-file instead. Note, the input file may also be specified as the last item on the command line. -P To compact all events and show the call graphs by ignoring tasks and different PIDs, add the -P to do so. Instead of showing the task name, it will group all chains together and show "<all pids>". SEE ALSO
trace-cmd(1), trace-cmd-record(1), trace-cmd-report(1), trace-cmd-start(1), trace-cmd-stop(1), trace-cmd-extract(1), trace-cmd-reset(1), trace-cmd-split(1), trace-cmd-listen(1) AUTHOR
Written by Steven Rostedt, <rostedt@goodmis.org[1]> RESOURCES
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/trace-cmd.git COPYING
Copyright (C) 2010 Red Hat, Inc. Free use of this software is granted under the terms of the GNU Public License (GPL). NOTES
1. rostedt@goodmis.org mailto:rostedt@goodmis.org 06/11/2014 TRACE-CMD-HIST(1)
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