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Jarwulf

awk in perl

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Jarwulf    223

Hi, I ran across this line in a perl file

 

system ("awk \'\$1 == \"$label\" && \$3 <= $apex && \$4 >= $apex\{print\}\' $reference >temp_marker_$name") ==0 or die "$0 failed to awk";

Does anyone have an idea of what its doing? It seems to be printing out if some comparisons are met is as far as I figure.

 

Also what is with a variable name like temp_marker_$name? Aren't scalar variables supposed to start with $ and not have them in the middle? What is the purpose of the slashes in the awk command?

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Ectara    3097

The way it looks is that the backslashes are escaping characters that would be recognized as syntactically significant in perl, so that those characters are passed as-is to awk. As far as temp_marker_$name, it seems to be expanding the value of $name in-place where it is referred to in the string, sort of like Bash scripting. This would result in a name like temp_marker_foo, if $name is holding the value of "foo".

 

As far as the actual purpose of the awk command's arguments, someone else will have to answer.

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