Berkeley CSUA MOTD:Entry 35545
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2017/10/18 [General] UID:1000 Activity:popular
10/18   

2005/1/4-5 [Computer/SW/Unix] UID:35545 Activity:moderate Edit_by:auto
1/4     Hello UNIX command line gurus, let's say I have a file called
        filenames.log that contains file names, like /usr/bin/hello,
        /media/dvd/wayne's world, /media/music/my music!.mpg. I'd like
        to do something like:
        % cat filenames.log | xargs tar rvf /backup/today.tar
        However, I can't do that because I need to escape characters
        like ', \ , \!, and many others. What's an elegant way of
        doing this? I thought about using sed, but I'd have to come
        up with a comprehensive list of characters that I have to
        escape, which is lame. Ideally I'd like something like:
        % cat filenames.log | escape | xargs rvf /backup/today.tar
        Got ideas? Thanks!
        \_ Here are a few ways to do it.  Hopefully you find one elegant.
           sed 's/[^A-Za-z0-9]/\\&/g' filenames.log | xargs tar rvf ...
           sed 's/./\\&/g' filenames.log | xargs tar rvf ...
           tr '\n' '\0' <filenames.log | xargs -0 tar rvf ...
           sed 's/[^A-Za-z0-9]/\\&/g' filenames.log | xargs tar rvf today.tar
           \_ thanks. So the above sed, with "&", is equivalent to
              perl's $1 or \1? It's seems like it's the same as perl's
              s/([^A-Za-z0-9])/\\$1/g;
              So here is another question. How do you specify $1, $2,
              etc in sed? thanks.
              \_ Sed's & is perl's $& (the entire search string).  Sed uses \1,
                 \2, etc. to retrieve stuff from parens.  Also note that you
                 have to use \( and \) in sed, not just ( and ) like in perl.
           sed 's/./\\&/g' filenames.log | xargs tar rvf today.tar
           tr '\n' '\0' <filenames.log | xargs -0 tar rvf today.tar
           tar rvfI today.tar filenames.log
        \_ % cat filenames.log | perl -ne 'print quotemeta;' |
             xargs rvf /backup/today.tar
             \-i'd use the tr command above to NULL pad + xargs -0 OR
               modify a perl script called "findtar" OR use GNU tar's
               -T|--files-from option possibly with --null. ok tnx --psb
             \_ if performance is an issue would perl be slower because the
                executable is bigger? Or would it be faster because it's
                got optimizations built in?
                \-no offense, but this is not a question worth asking.
                  or at least not worth answering.
        \_ xargs is wrong in this case. Use normal tar with -T. -vadim
           \- tar -rv -f mybackup.tar -T file_list.txt
        \_ keywords: perl escape character space
ERROR, url_link recursive (eces.Colorado.EDU/secure/mindterm2) 2017/10/18 [General] UID:1000 Activity:popular
10/18   

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