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Full Discussion: Bash : Checking Large file for specific lines
Top Forums Shell Programming and Scripting Bash : Checking Large file for specific lines Post 303019069 by rbatte1 on Friday 22nd of June 2018 12:24:49 PM
Old 06-22-2018
I would go further:-
Code:
if $(grep -q "now is the time" 1000linefile.txt)
then
   echo "It's a HIT"
else
   echo "Missed"
fi

The extra benefit is that the -q flag will cause the grep to exit immediately that it has matched, so if you have a properly large file (more than just a few disk blocks), it won't have to read it all if it finds a match, saving you IO time.

Potentially you could extend the search using an expression, but that's up to you knowing what you are looking for. If you want to know the state of each you would have to run twice right through the file. If you want to know if either is listed, then:-
Code:
if $(egrep -q "now is the time|for all good men" 1000linefile.txt)
then
   echo "It's a HIT"
else
   echo "Missed"
fi




I hope that this helps,
Robin
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LEARN ABOUT V7

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  invokes  grep  on  compressed  or  gzipped  files.   These  grep	options  will  cause  zgrep  to  terminate  with  an  error  code:
       (-[drRzZ]|--di*|--exc*|--inc*|--rec*|--nu*).  All other options specified are passed directly to grep.  If no file is specified,  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 the GREP environment variable is set, zgrep uses it as the grep program to be invoked.

EXIT CODE

       2 - An option that is not supported was specified.

AUTHOR

       Charles Levert (charles@comm.polymtl.ca)

SEE ALSO

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

																	  ZGREP(1)
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