On 12 Jan 2012 at 20:34:26, Mark LaPierre wrote: > On 01/12/2012 02:13 PM, Anthony R Fletcher wrote: > > On 12 Jan 2012 at 14:02:50, Dean S. Messing wrote: > >> > >> In a system script I find this snippet > >> > >> nodevs=$(< /proc/filesystems fgrep rootfs) > >> > >> and don't understand the syntax. According to the bash man page, > >> > >> $(< file) is shorthand for $(cat file). But then the above should read > >> > >> nodevs=$(< /proc/filesystems | fgrep rootfs) > >> > >> However, the latter leaves $nodevs empty whereas the former puts the > >> stuff that fgrep processes into nodevs as it should. > > > > > > The command > > < /proc/filesystems fgrep rootfs > > > > redirects the input from the file /proc/filesystems into the command > > "fgrep rootfs". You could rewrite this as > > fgrep rootfs< /proc/filesystems > > > > nodevs=$( command ) takes the result of the command inside the > > parentheses and assigns into the variable nodevs. > > > > Anthony. > > > > or you could do: > > nodevs=`fgrep rootfs /proc/filesystems` > > The only problem is that putting the command inside ticks launches a > child process that consumes additional resources. Correct. But I lied slightly. What was actually in the script was: nodevs=$(< /proc/filesystems awk ...) where ... was complicated. I wanted to simply the issue so I subbed something trivial for the command. Dean -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines Have a question? Ask away: http://ask.fedoraproject.org
