tee to a file descriptor
|
|
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![\"Screenshot](\"http://commons.wikipedia.org/wiki/Image:Bash_demo.png\" "\\"Screenshot")
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