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



The man pages were written for people who already know what the commands For "awk" this is more true than most Eunichs commands..


On Mar 28, 2007, at 8:18 PM, Malcolm Fitzgerald wrote:


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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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>)
 >Re: Shell grep help - how to get only first occurrence of match? (From: Malcolm Fitzgerald <email@hidden>)



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