regular expressions and setting variables?

regular expressions and setting variables?

[William G. Scott]

Hi folks:

I’m trying to emulate how iTunes changes some names of directories it creates based on names of artists.  For example, albums by the group R.E.M. are stored in a directory it creates called R.E.M_  

The final full-stop is replaced with an underscore, I assume to avoid complications in the unix filesystem.


This works:
  
 JUNK=R.E.M.
 print ${JUNK}| perl -p -e 's|\.$|_|g’

It returns
R.E.M_


But if I try to do this:  

print ${JUNK/\.$/_}   

it returns               
R.E.M.
 
I assume I am not using the correct regexp.  What do I need to do to get this working?

Thanks in advance.

Bill Scott

regular expressions and setting variables?

[William G. Scott]

Hi folks:

I’m trying to emulate how iTunes changes some names of directories it creates based on names of artists.  For example, albums by the group R.E.M. are stored in a directory it creates called R.E.M_  

The final full-stop is replaced with an underscore, I assume to avoid complications in the unix filesystem.


This works:

JUNK=R.E.M.
print ${JUNK}| perl -p -e 's|\.$|_|g’

It returns
R.E.M_


But if I try to do this:  

print ${JUNK/\.$/_}   

it returns               
R.E.M.

I assume I am not using the correct regexp.  What do I need to do to get this working?

Thanks in advance.

Bill Scott

Re: regular expressions and setting variables?

[Roman Neuhauser]

# wgscott@ucsc.edu / 2014-06-09 22:04:20 -0700:
> I?m trying to emulate how iTunes changes some names of directories it
> creates based on names of artists.  For example, albums by the group
> R.E.M. are stored in a directory it creates called R.E.M_  
> 
> The final full-stop is replaced with an underscore, I assume to avoid
> complications in the unix filesystem.

i doubt that.  "the unix filesystem" does not care about names at all,
well, almost: a filename cannot contain slashes and null bytes.
slash, because these are used to separate "foo" from "bar" in "foo/bar",
and null bytes, because "foo" and "bar" are stored in the filesystem
as C strings, where the null byte is used as terminator.

windows filesystems OTOH, among other limitations, prohibit names
ending with a dot.

> This works:
> 
> JUNK=R.E.M.
> print ${JUNK}| perl -p -e 's|\.$|_|g?
> 
> It returns
> R.E.M_
> 
> 
> But if I try to do this:  
> 
> print ${JUNK/\.$/_}   
> 
> it returns               
> R.E.M.
> 
> I assume I am not using the correct regexp.

kinda, the ${param/pat/rep} operation does not use regexps, the pattern
expects the globbing ("filename generation") syntax.

> What do I need to do to get this working?

man zshexpn.

-- 
roman

Re: regular expressions and setting variables?

[Phil Pennock]

On 2014-06-09 at 22:04 -0700, William G. Scott wrote:
> This works:
> 
> JUNK=R.E.M.
> print ${JUNK}| perl -p -e 's|\.$|_|g’
> 
> It returns
> R.E.M_
> 
> 
> But if I try to do this:  
> 
> print ${JUNK/\.$/_}   
> 
> it returns               
> R.E.M.
> 
> I assume I am not using the correct regexp.  What do I need to do to get this working?

${name/pattern/repl} does not use regular expressions, it uses shell
patterns.

Described in zshexpn(1) under "PARAMETER EXPANSION".

% echo ${JUNK/%./_}
R.E.M_

-Phil

Re: regular expressions and setting variables?

[William G. Scott]

On Jun 10, 2014, at 1:45 AM, Phil Pennock <zsh-workers+phil.pennock@spodhuis.org> wrote:

> 
> ${name/pattern/repl} does not use regular expressions, it uses shell
> patterns.
> 
> Described in zshexpn(1) under "PARAMETER EXPANSION".
> 
> % echo ${JUNK/%./_}
> R.E.M_
> 
> -Phil


Thanks very much to all who replied.  I didn’t even realize there was a difference (sorry).

— Bill

Re: regular expressions and setting variables?

[zzapper]

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"William G. Scott" <wgscott@ucsc.edu> wrote in
news:157E3510-D220-4C1C-A452-93DE96DA4363@chemistry.ucsc.edu:

> Hi folks:
>
> I’m trying to emulate how iTunes changes some names of directories it
> creates based on names of artists.  For example, albums by the group
> R.E.M. are stored in a directory it creates called R.E.M_
>
> The final full-stop is replaced with an underscore, I assume to avoid
:
>
> JUNK=R.E.M.
> print ${JUNK}| perl -p -e 's|\.$|_|g’
>
> It returns
> R.E.M_
>
>
> But if I try to do this:
>
> print ${JUNK/\.$/_}
>

JUNK=R.E.M.
print ${JUNK/\.(#e)/\_}




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