[mdlug] GNU sed weirdness

[Dennis VanHoey]

have you tried using the forward slash instead? (not that I have recently
used sed) but normally gnu tools will accept a forward slash and translate
it internally.

On Sat, Jan 23, 2010 at 9:11 PM, Jeff Hanson <jhansonxi at gmail.com> wrote:

> With GNU sed on Ubuntu 8.04 I'm wrote a simple script that takes in a
> Windows full-path file listing and changes it to a Windows 7-zip
> compression batch file.  It uses back references get the parent
> directory path and filename.  There are several files that have the
> same name but with different extensions and I just want to put all the
> ones that match by filename into the same 7z file.  I wanted to use
> variables for the 7-zip path, target directory, and compression
> options.  Because of spaces in the directory and file names I need to
> embed quotes.  To keep the sed command from getting really ugly I
> split it up into a single-quoted search, double-quoted (because of
> variable expansions) replacement for the variables followed by
> single-quoted replacement for the back references.  The back
> references \1 holds the directory path and \2 holds the filename
> without extension.  What I though was the correct form looks like
> this:
>
> sed -n 's/\(.*\)\\\(.*\)\.idx/'"\"$compress_exe\" $compress_opts
> \"$target_dir\\"'\2'".$compress_ext"'\" \"\1\\2.*\"/p' $1
>
> Broken up:
> sed -n 's/\(.*\)\\\(.*\)\.idx/'
> "\"$compress_exe\" $compress_opts \"$target_dir\\"
> '\2'
> ".$compress_ext"
> '\" \"\1\\2.*\"/p' $1
>
> Basic input is:
> compress_exe='c:\\Program Files\\7-Zip\\7z.exe'
> compress_ext='7z'
> compress_opts='a -mx=7 -ms=on -wD:\\'
> target_dir='D:\\archive'
>
> filelist.txt ($1):
> D:\data\20100123.idx (the directory contains several other files with
> the same path/name but with different extensions)
> ...
>
> Desired output is:
> "c:\Program Files\7-Zip\7z.exe" a -mx=7 -ms=on -wD:\
> "D:\archive\20100123.7z" "D:\data\20100123.*"
>
> Not too complicated but it doesn't work.  I tried different quotes and
> escape orders but always end up with:
> "c:\Program Files\7-Zip\7z.exe" a -mx=7 -ms=on -wD:\ "D:\archive\2.7z"
> "D:\data\20100123.*"
>
> For some reason it seems that sed gets confused by the double-quoted
> escaped backslash and the following single-quoted back reference \2.
> Either it prints nothing or uses the back reference index literally.
> The only way I could get it to work was to move the backslash into the
> variable instead:
>
> target_dir='D:\\archive\\'
>
> sed -n 's/\(.*\)\\\(.*\)\.idx/'"\"$compress_exe\" $compress_opts
> \"$target_dir"'\2'".$compress_ext"'\" \"\1\2.*\"/p' $1
>
> This worked.  Is there something fundamental I'm overlooking with the
> earlier version or is it a bug?
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