Understanding Awk and Cat

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# 1  
Old 07-27-2009
Understanding Awk and Cat

Hi Guys,

I was recently come across some code to hopefully learn a little bit about putting Shell commands into PHP application to run on a Linux server. However, I don't understand the command AT ALL... and was wondering if anyone can interpret it:

cat userIDs.dat | awk '{s=s+1; if (s==$end) print $0; if (s > $start && s < $end) printf \"%s,\", $0}' > path/to/file/to/store/in/IDS.file

It doesn't seem to do anything, but I may have put an error in there, when making it applicable to my directories etc. I have no clue!

Any light you guys can shed on this would be great!

Thank you,
# 2  
Old 07-27-2009
awk won't understand the shell variables.
you have to tell awk that those are shell variables.

so in your case "$end", "$start" etc are not being replaced by the actual values.

user double quotes or -v flag.

awk -v START="$start" -v END="$end" '{s=s+1; if (s==END) print $0; if (s > START && s < END) printf \"%s,\", $0}' > path/to/file/to/store/in/IDS.file

if you are facing problem related to your requirement, then please post your sample "IDS.file" and require output ( conditions).
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