LinuxQuestions.org - [SOLVED] sed problems. possibly delimiter related

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sed problems. possibly delimiter related

I am creating a script that pulls out certain path+files that get dumped from ldd. so as an example, say the program is named "cheezewiz".

Code:

$ ldd cheezewiz

        libQtGui.so.4 => /usr/lib/x86_64-linux-gnu/libQtGui.so.4 (0x00007fcca6c37000)

        libQtDBus.so.4 => /usr/lib/x86_64-linux-gnu/libQtDBus.so.4 (0x00007fcca69ba000)

        libQtXml.so.4 => /usr/lib/x86_64-linux-gnu/libQtXml.so.4 (0x00007fcca6777000)

        libQtSql.so.4 => /usr/lib/x86_64-linux-gnu/libQtSql.so.4 (0x00007fcca6537000)

        libQtCore.so.4 => /usr/lib/x86_64-linux-gnu/libQtCore.so.4 (0x00007fcca6065000)

What is to be pulled out is the path and file from each line, and erase the rest. (1st line example "/usr/lib/x86_64-linux-gnu/libQtGui.so.4")

I'm guessing a proper way to do this would use the "=> " as the first search point and the " (0" as the end. However I'm not sure how to extract this, nor what option would be best in sed. The main problem for me is I'm not sure if the => are special chars that need a "\" or what to do because the things that are searched for contain "/".

Does anyone have any tips or suggestions for how to approach this? I'd really apprecheate any response.

There are lots of ways to kill this bird. The easiest is probably awk.

Code:

ldd cheezewiz | awk '/=>/{print $3}'

But if you really want to use sed, here are a couple of versions that should work too]

Code:

ldd cheezewiz | sed -rn '/=>/ s/.*=> ([^ ]+) .*/\1/p'

ldd cheezewiz | sed -rn '/=>/ s/(^.*=> | [(].*$)//gp'

By the way, sed's substitution delimiter can be any ascii character, not just '/'. It will use whatever comes directly after the 's', so just use something that doesn't appear in the expression itself. And no, '=' and '>' are not regex special.

Here are a few useful sed references:
http://www.grymoire.com/Unix/Sed.html
http://sed.sourceforge.net/grabbag/
http://sed.sourceforge.net/sedfaq.html
http://sed.sourceforge.net/sed1line.txt
http://www.catonmat.net/series/sed-one-liners-explained

=====
Here are a few useful awk references:
http://www.grymoire.com/Unix/Awk.html
http://www.gnu.org/software/gawk/man...ode/index.html
http://www.pement.org/awk/awk1line.txt
http://www.catonmat.net/series/awk-one-liners-explained

=====
Here are a few regular expressions tutorials:
http://mywiki.wooledge.org/RegularExpression
http://www.grymoire.com/Unix/Regular.html
http://www.regular-expressions.info/

This is the most resilient method I've found:

Code:

ldd calcoo | sed 's/.*=> //' | awk '{ print $1 }'

It passes things like:

Code:

        linux-vdso.so.1 (0x00007fff283bf000)

        libgtk-x11-2.0.so.0 => /usr/lib64/libgtk-x11-2.0.so.0 (0x00007f7b1e140000)

        libgdk-x11-2.0.so.0 => /usr/lib64/libgdk-x11-2.0.so.0 (0x00007f7b1de8e000)

        librt.so.1 => /lib64/librt.so.1 (0x00007f7b184ef000)

        /lib64/ld-linux-x86-64.so.2 (0x00007f7b1e78e000)

        libgcc_s.so.1 => /usr/lib64/libgcc_s.so.1 (0x00007f7b182d8000)

Actually, I'd say the second sed command I posted is probably the most reliable. It simply removes everything before and after the desired string, matching them with clearly defined regexes. And all in a single process.

If it's a bit difficult to comprehend, it can also be written this way, with two separate substitutions:

Code:

ldd cheezewiz | sed -n '/=>/ { s/^.*=> // ; s/ [(].*$// ; p }'

Thank you David the H. and H_TeXMeX_H, both work great. As for the links, it seems everytime I need to use sed for something like this it ends up getting figured out, however the very next time I need to use it again, little or nothing from the past can help with a new problem.

I'm checking out the sourceforge grabbag now. Best regards and thanks again for your help!

Yeah, it does take time and effort to gain experience with the tools you use. I know that I had some hair-pulling times myself (still do, occasionally). Just keep plugging away, and it'll eventually get easier.