trying to convert from awk to perl

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

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Re: trying to convert from awk to perl by merlyn (Sage) on Jan 09, 2006 at 16:40 UTC
Your question has already been asked and answered on comp.lang.perl.misc. You've even responded there, and gotten additional assistance. It's rude to reinsert the original problem into a new venue without proper disclosure. -- Randal L. Schwartz, Perl hacker Be sure to read my standard disclaimer if this is a reply.	[reply]
Re: trying to convert from awk to perl by explorer (Chaplain) on Jan 09, 2006 at 16:44 UTC
`awk '$1 ~ /^F/ { print $0 }' /tmp/frhtest/ADDC.bak > /tmp/frhtes +t/ADDC.$date perl -ane 'print if $F[0] =~ /^F/' /tmp/frhtest/ADDC.bak > /tmp/frhtes +t/ADDC.$date` [download]	[reply] [d/l]
Re: trying to convert from awk to perl by smokemachine (Hermit) on Jan 09, 2006 at 17:34 UTC
`perl -ne 'print if /^F/' /tmp/frhtest/ADDC.bak > /tmp/frhtest/ADDC.$da +te` [download]	[reply] [d/l]
Re: trying to convert from awk to perl by Perl Mouse (Chaplain) on Jan 09, 2006 at 22:52 UTC
The problem you are suffering from is that fact that the backticks are an interpolative context. Which means that the `$1` you have is interpolated before the call to `awk` is made. And you have the same for the `$0`. Putting backslashes before the dollar signs will solve this problem. However, it doesn't make sense to use backticks here. Backticks run the command, and return the output of the command - however, since your command redirects all output, there's nothing to collect. The following `system` command you make doesn't make sense - it executes nothing. You'd be better off to use `system` here, instead of the backticks - and then you can `q` and avoid `$1` and `$0` to be interpolated: `system q {awk '$1 ~ /^F/ {print $0 }' /tmp/frhtest/ADDC.bak > /tmp/frh +test/ADDC.}.$date; die "Command failed" if $?;` [download] `Perl --((8:>*`	[reply] [d/l] [select]
Re: trying to convert from awk to perl by runrig (Abbot) on Jan 09, 2006 at 17:47 UTC
Your awk program is more verbose than it needs to be. The default action is to `print $0`, and since all you're doing is matching `$1` at the beginning of the string, ~~you may as well be matching `$0`~~. So your awk program could just be: `awk '/^F/' # Correction...should be awk '$1 ~ /^F/'` [download] And actually, there's no reason you couldn't just use grep for this. Update: ambrus is correct below. Oops.	[reply] [d/l] [select]
Re^2: trying to convert from awk to perl by ambrus (Abbot) on Jan 09, 2006 at 19:32 UTC
and since all you're doing is matching $1 at the beginning of the string, you may as well be matching $0. That's not true, the line `Foo` [download] will not match `/^F/` but as the leading space doesn't get into `$1`, `$1 ~ /^F/` will be true.	[reply] [d/l] [select]
Re: trying to convert from awk to perl by thor (Priest) on Jan 10, 2006 at 05:01 UTC
In general, the program a2p that ships with perl is a good first step for converting awk to perl... thor `The only easy day was yesterday`	[reply]