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Full Discussion: Help in printing records where there is a 'header' in the first record ???
Top Forums UNIX for Beginners Questions & Answers Help in printing records where there is a 'header' in the first record ??? Post 303010167 by Don Cragun on Thursday 28th of December 2017 01:41:42 AM
Old 12-28-2017
The grep -v "^$" is NOT just a sanity thing. It is a waste of system resources that only serves to make your script run slower. Any line that is matched by the first grep in your pipeline can't possibly be an empty line that will be discarded by the second grep in your pipeline. The cat in your pipeline is an unnecessary use of cat. It, again, only serves to make your script run slower.

The following script produces the same output as your script. But, of course, it depends on your sample input being a realistic sample of the actual contents of /tmp/x.txt. If it isn't, all bets are off.

Code:
awk 'sub(/^.*xx_tmp/, "xx_tmp")' /tmp/x.txt

This User Gave Thanks to Don Cragun For This Post:
Neo
 

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LEARN ABOUT V7

pr

PR(1)							      General Commands Manual							     PR(1)

NAME

       pr  -  print file

SYNOPSIS

       pr [ option ] ...  [ file ] ...

DESCRIPTION

       Pr  produces a printed listing of one or more files.  The output is separated into pages headed by a date, the name of the file or a speci-
       fied header, and the page number.  If there are no file arguments, pr prints its standard input.

       Options apply to all following files but may be reset between files:

       -n     Produce n-column output.

       +n     Begin printing with page n.

       -h     Take the next argument as a page header.

       -wn    For purposes of multi-column output, take the width of the page to be n characters instead of the default 72.

       -ln    Take the length of the page to be n lines instead of the default 66.

       -t     Do not print the 5-line header or the 5-line trailer normally supplied for each page.

       -sc    Separate columns by the single character c instead of by the appropriate amount of white space.  A missing c is taken to be a tab.

       -m     Print all files simultaneously, each in one column,

       Inter-terminal messages via write(1) are forbidden during a pr.

FILES

       /dev/tty?  to suspend messages.

SEE ALSO

       cat(1)

DIAGNOSTICS

       There are no diagnostics when pr is printing on a terminal.

																	     PR(1)
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