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Passing command line arguments to awk

Posted on 1998-06-23
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How can I pass a command line argument such as $1 or $2 into an awk script?

I have written a shell script that includes some awk programming and i need to be able to call that program by typing ./program inputword and then search for inputword within awk.

For example, if I had a datafile with the following contents:

a:b:c:d:e:f:g:
g:f:e:d:c:b:a:

and i wanted to write a script to search through that file for a name that I give at the command line

awk '
$4 ~ /b/ {print $4} ' datafile

i would like to do it like this

awk '
$4 ~ /input from command line such as $1/ {print $4}' datafile

I have tried this:

awk '
$4 ~ /inputword/ {print $4}' inputword=$1 datafile

without any luck

I have to be able to run the program without having to type something like

awk -f scriptfile datafile

as it gets to confusing.

Can anyone help?


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Question by:ianfoster
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5 Comments
 
LVL 51

Accepted Solution

by:
ahoffmann earned 400 total points
ID: 1294239
2 possibilities:

1. use gawk -v varname=inputword -f awkscript datafile
   (use  varname in you awk script)

2. using traditional awk is somehow triky, you must pass in you
   strings via the data stream and then identify it uniqely
   example:

   /^SPECIAL_VALUE/ { inputword = $2; next; }
   {   # rest of script }

   call this script as follows:

   (echo SPECIAL_VALUE "your_value"; cat datafile)|awk -f script

   Keep in mind that SPECIAL_VALUE *must not* appear in datafile.
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LVL 51

Expert Comment

by:ahoffmann
ID: 1294240
(echo SPECIAL_VALUE inputword; cat datafile) | awk '/^SPECIAL_VALUE/ { pattern=$2;} $4 ~ pattern {print $4}'
0
 
LVL 84

Expert Comment

by:ozo
ID: 1294241
awk "\$4 ~ /$1/ {print \$4}"  datafile
0
 

Author Comment

by:ianfoster
ID: 1294242
I've installed gawk on the machine but still no luck :(


Here's another example:


--------------------

#!/bin/sh

echo "Here we go!"

# the rest of the shell script goes here


gawk -v input=$1 -F: '
$1 ~ /input/ {print $1}' datafile

--------------------


datafile contents as follows

a:b:c:d:
a:b:c:d:
a:b:c:d:

I call the program as follows

/gawkprog a

it should print out "a" for each line but I get nothing.

it does read in the $1 part because I can do this                  

gawk -v input=$1 -F: '
{print input} ' datafile

and run it ./gawkprog a

and it will print out

a
a
a

so the problem seems to be that gawk doesnt like matching things with
the input part.

any ideas?
0
 
LVL 51

Expert Comment

by:ahoffmann
ID: 1294243
gawk -v input=$1 -F: '$1 ~ input {print $1}' datafile

BTW, ozo's solution works also inside a shell script
0

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