$` $' in bash??

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

Hello monks, I was wondering if there is a way to use $` and $' in bash commands... lets say

perl -lane '$F[1]=~s/(chr\w[^_]?)_.*\b/$1/;print $`. "\t". $F[1] ."\t" .$'' (which does not work because the apostrophe ends the executable... \' doesn't work either) .

Also why is it that \1 doesn't work... is using $1 the correct way to do this? If anyone knows of a reference that documents what special characters translate to bash commands it would be very appreciated. Thank you for your help.

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Re: $` $' in bash?? by ikegami (Patriarch) on Jul 20, 2011 at 18:01 UTC
There's no issue with «`» (within single quotes). The problem is with «`'`». Ways of making «foo$'bar$`baz» into a bash literal: foo\$\'bar\$\`baz "foo\$'bar\$`baz" 'foo$'"'"'bar$`baz' 'foo$'\''bar$`baz' [download] Of course, you could use avoid using «`'`», starting by writing code that's much clearer. `perl -lanE'$F[1]=~/(.?)(chr\w[^_]?)_.\b(.)/; say "$1\t$1$2$3\t$3"'` [download] The pattern looks very fishy. `/.\b.*/`? There are clearer and safer ways of writing that. I have no idea what you are trying to match with that.	[reply] [d/l] [select]
Re: $` $' in bash?? by Sandy (Curate) on Jul 20, 2011 at 17:22 UTC
use English `perl -lane 'use English;$F[1]=~s/(chr\w[^_]?)_.*\b/$1/;print $PREMATC +H. "\t". $F[1] ."\t" .$POSTMATCH'` [download]	[reply] [d/l]
Re^2: $` $' in bash?? by ikegami (Patriarch) on Jul 20, 2011 at 18:12 UTC
It's silly to keep using the bad variables instead of /p if you're going to use the English names. `perl -lane '$F[1]=~s/(chr\w[^_]?)_.*\b/$1/p;print ${^PREMATCH}. "\t". +$F[1] ."\t" .${^POSTMATCH}'` [download]	[reply] [d/l]
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
Re: $` $' in bash?? by JavaFan (Canon) on Jul 20, 2011 at 20:16 UTC
Using a standard trick to include a single quote: perl -lane '$F[1]=~s/(chr\w[^_]?)_.*\b/$1/;print $`. "\t". $F[1] ."\t" + .$'"'" [download] The single quote directly following the $ matches the first single quote. In Perl, this will end a string, but not so in the shell - here single quotes act like `\Q`/`\E` in Perl. Directly following the $ and the single quote is `"'"`, which for the shell is just a single quote. Which makes that the Perl program ends in `$'`, as intended.	[reply] [d/l] [select]


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