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.
--
_
°v°
/(_)\
^ ^ Mark LaPierre
Registerd Linux user No #267004
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