How to negate grep result? Post: 302191856

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Top Forums Shell Programming and Scripting How to negate grep result? Post 302191856 by drl on Monday 5th of May 2008 06:45:25 AM

05-05-2008

Registered User

Hi.

It looks like you are using the csh family and you wish to know how to run a command and test the exit status in an if. Most people agree that members of the csh family are not good for scripting because of technical drawbacks and flaws. The Bourne shell family is considered superior for scripting.

However, if you must use csh, you can use braces to obtain the exit status of a command:

Code:

#!/bin/csh

# @(#) s2       Demonstrate csh braces: run command, test exit status.

# Create a scratch file if one does not exist.
touch t1

echo
if ( { ls t1 } ) then
        echo " command ls succeeded."
else
        echo " command ls FAILED."
endif

# Remove file.
rm t1

echo
if ( { ls t1 } ) then
        echo " command ls succeeded."
else
        echo " command ls FAILED."
endif

exit $status

Producing:

Code:

% ./s2

t1
 command ls succeeded.

ls: t1: No such file or directory
 command ls FAILED.

Another method is to run the command outside the if, and set a variable to the exit status variable $status. That is something you can try on your own. See man csh for details -- it's long, but if you continue to use csh, you should know about the features ... cheers, drl

drl

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LEARN ABOUT REDHAT

zgrep

ZGREP(1)						      General Commands Manual							  ZGREP(1)

NAME

       zgrep - search possibly compressed files for a regular expression

SYNOPSIS

       zgrep [ grep_options ] [ -e ] pattern filename...

DESCRIPTION

       Zgrep  is used to invoke the grep on compress'ed or gzip'ed files. All options specified are passed directly to grep.  If no file is speci-
       fied, then the standard input is decompressed if necessary and fed to grep.  Otherwise the given files are uncompressed	if  necessary  and
       fed to grep.

       If  zgrep  is invoked as zegrep or zfgrep then egrep or fgrep is used instead of grep.  If the GREP environment variable is set, zgrep uses
       it as the grep program to be invoked. For example:

	   for sh:  GREP=fgrep	zgrep string files
	   for csh: (setenv GREP fgrep; zgrep string files)

AUTHOR

       Charles Levert (charles@comm.polymtl.ca)

SEE ALSO

       grep(1), egrep(1), fgrep(1), zdiff(1), zmore(1), znew(1), zforce(1), gzip(1), gzexe(1)

																	  ZGREP(1)

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