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Full Discussion: grep variables nested within grep
Top Forums Shell Programming and Scripting grep variables nested within grep Post 302440949 by zaxxon on Thursday 29th of July 2010 02:59:09 AM
Old 07-29-2010
Some general things to note:
  • There is no need to cat files via pipe into other commands when they can take files as parameter themselves. You save a command and for time critical tasks you might want to spare all out you don't really need.
  • awk can "grep" too. It is one of it's easiest jobs to match patterns. You could write all those greps with one awk.
  • If not enclosed by single quotes, a variable will be substituted by the shell. There is no need to write `echo $VAR` to use the variables content as pattern.

For the problem that the content of your variable is not being passed, you should make sure 1st, that the content of the variable is the one you expect, before you pass it and if the grep/awk can match anything with this pattern.
A simple echo in the line after the declaration of the variable would be sufficient to check it out:

Code:
...
Thread_serialnum_time=...
echo $Thread_serialnum_time
...

Here an example how you could write such a lengthy pipe column instead:
Code:
# original
outtime=$(cat masterlogfile.txt | grep 'Leaving callExitsIn 2'| grep `echo $Thread_count` | grep `echo $Thread_serialnum_time` | awk  '{ print $2 }')

# how it could look like with just 1 command
outtime=$(awk '/Leaving callExitsIn 2/ && /'${Thread_count}'/ && /'${Thread_serialnum_time}'/ {print $2}' masterlogfile.txt)

 

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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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