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Re: Shell grep help - how to get only first occurrence of match?
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Re: Shell grep help - how to get only first occurrence of match?


  • Subject: Re: Shell grep help - how to get only first occurrence of match?
  • From: Malcolm Fitzgerald <email@hidden>
  • Date: Thu, 29 Mar 2007 10:18:13 +1000


On 29/03/2007, at 3:57 AM, Mark J. Reed wrote:

If you have columns of data separated by arbitrary amounts of
whitespace, the command you're looking for is awk, rather than grep.

awk '{print $1}' will print the first column of every line.  $2 for
the second, etc.
$NF (short for "Number of Fields") for the last column, $(NF-1) for
the second-to-last, etc.
$0 is the whole line.

you can stick /pattern/ in front of the {...} block to run it only for
lines matching that pattern, e.g.

awk '/[0-9]/ {print $1}'  will print the first column of all lines
that contain a digit anywhere in the line.  Note that this means it is
never necessary to do grep | awk. :)


Wow, it's that easy. You wouldn't know it from the man page.

malcolm

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  • Follow-Ups:
    • Re: Shell grep help - how to get only first occurrence of match?
      • From: "Mark J. Reed" <email@hidden>
    • Re: Shell grep help - how to get only first occurrence of match?
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References: 
 >Re: Shell script help - get date of last modified file in hierarchy (From: "Mark J. Reed" <email@hidden>)
 >Shell grep help - how to get only first occurrence of match? (From: Richard Rönnbäck <email@hidden>)
 >Re: Shell grep help - how to get only first occurrence of match? (From: "Mark J. Reed" <email@hidden>)

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