Re^2: $` $' in bash??

It's silly to keep using the bad variables instead of /p if you're going to use the English names.

perl -lane '$F[1]=~s/(chr\w[^_]?)_.*\b/$1/p;print ${^PREMATCH}. "\t". 
+$F[1] ."\t" .${^POSTMATCH}'
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Re^3: $` $' in bash?? by Sandy (Curate) on Jul 21, 2011 at 16:37 UTC
Actually, I never `use English`, so I am not sure what it is that you are saying. bad variables?? What is the reason for using `${^PREMATCH}` instead of `$PREMATCH`?	[reply] [d/l] [select]
Re^4: $` $' in bash?? by ikegami (Patriarch) on Jul 21, 2011 at 19:49 UTC
I never use English, so I am not sure what it is that you are saying. You did in the post to which I replied. What is the reason for using ${^PREMATCH} instead of $PREMATCH? Quote perlre: "Once Perl sees that you need one of $& , $` , or $' anywhere in the program, it has to provide them for every pattern match. This may substantially slow your program." ${^PREMATCH} and the like are only set on demand (/p), so Perl doesn't need to preemptively populate it whenever you perform a match.	[reply]