intercept stdout/stderr of another process or disowned process

2010-11-23 1 min read Bash Fedora Linux

The command is definately going to save your day if you have disowned the process by mistake. Only uses strace so might as well work on Solaris also, though not tried it.

intercept stdout/stderr of another process or disowned process

  <td>
    <div class="text codecolorer">
      strace -e write=1,2 -p $PID 2>&1 | sed -un "/^ |/p" | sed -ue "s/^.{9 }(.{50}).+/1/g" -e 's/ //g' | xxd -r -p
    </div>
  </td>
</tr>
1

Useful to recover a output(stdout and stderr) “disown”ed or “nohup“ep process of other instance of ssh.

Continue reading

tee to a file descriptor

2010-08-13 1 min read Bash Linux

tee to a file descriptor

1
$ tee >(cat &#8211; >&2)

the tee command does fine with file names, but not so much with file descriptors, such as &2. This uses process redirection to tee to the specified descriptor.

In the sample output, it’s being used to tee to stderr, which is connected with the terminal, and to wc -l, which is also outputting to the terminal. The result is the output of bash –version followed by the linecount

Continue reading

coproc help - a new feature in bash

2010-05-10 0 min read Bash Fedora Linux
\"Screenshot
Image via Wikipedia

In the <a class="zem_slink freebase/en/bash" title="Bash" rel="homepage" href="http://tiswww.case.edu/php/chet/bash/bashtop.html">bash version 4.0, there is a new concept called coproc. This is very useful for some of the daily tasks.

co-<a class="zem_slink freebase/guid/9202a8c04000641f800000000005a409" title="Process (computing)" rel="wikipedia" href="http://en.wikipedia.org/wiki/Process_%28computing%29">process starts a process in the background, optionally with a NAME, with which other processes can communicate. This can be a very <a class="zem_slink freebase/en/substitute_good" title="Substitute good" rel="wikipedia" href="http://en.wikipedia.org/wiki/Substitute_good">good substitution for <a class="zem_slink freebase/guid/9202a8c04000641f800000000048fac5" title="Pipeline (Unix)" rel="wikipedia" href="http://en.wikipedia.org/wiki/Pipeline_%28Unix%29">pipes in lots of cases. You can learn more about coproc in the link below:

Continue reading

prepend to a file with sponge from moreutils

2010-03-16 1 min read Linux

<a href="http://bashcurescancer.com/prepend-to-a-file-with-sponge-from-moreutils.html">A few weeks I wrote about a tool, which helps you easily prepend to a file. I submitted prepend to moreutils and Joey was kind enough to point out this could be done with `sponge&#8217;.? sponge reads standard input and when done, writes it to a file:
Probably the most general …<h6 class="zemanta-related-title">Related articles by Zemanta <ul class="zemanta-article-ul"> <li class="zemanta-article-ul-li"><a href="http://helpdeskgeek.com/linux-tips/crontab-howto-tutorial-syntax/">Automating Tasks in Linux Using Crontab (helpdeskgeek.com) <li class="zemanta-article-ul-li"><a href="http://www.slideshare.net/progrium/sxsw-evented-web">How WebHooks Will Make Us All Programmers (slideshare.net) <li class="zemanta-article-ul-li"><a href="http://almirkaric.com/2010/01/07/debugging-python-multiprocessing/">Debugging python (multi)processing (almirkaric.com) <li class="zemanta-article-ul-li"><a href="http://www.slideshare.net/royzimmer/you-can-do-it-start-using-perl-to-handle-your-voyager-needs">You Can Do It! Start Using Perl to Handle Your Voyager Needs (slideshare.net) <div class="zemanta-pixie"><a class="zemanta-pixie-a" title="Reblog this post [with Zemanta]" href="http://reblog.zemanta.com/zemified/b2b2afad-1679-46ab-831c-90ae0cc4d30f/"><img class="zemanta-pixie-img" src="http://blog.amit-agarwal.co.in/wp-content/uploads/2010/08/reblog_b14.png" alt="Reblog this post [with Zemanta]" /><span class="zem-script more-related more-info pretty-attribution paragraph-reblog">

Continue reading
Newer posts