command to run another command on a few lines

[pareshverma91]

hi all,
can someone tell me a command which can be used to run some other command on a few lines from a file or an o/p of some file.
(the kind of role that -exec option does for the find command)
(i have solved the purpose using a bash loop but would like to know if there exists a command)
Thanks

[Franklin52]

hi all,
can someone tell me a command which can be used to run some other command on a few lines from a file or an o/p of some file.
(the kind of role that -exec option does for the find command)
(i have solved the purpose using a bash loop but would like to know if there exists a command)
Thanks

To run commands from a file:

sh file

from the output of a command:

command | sh

[pareshverma91]

I think i didnt explain my problem clearly.
what i meant was that suppose a file contains lines as:
234
3245

now i want to kill the processes with above id
so how do i do it....
( i have found a way as "kill -9 `cat filename`" but i remember reading out somewhere that using "`" is not desirable)

[Franklin52]

I should be careful with kill -9 but you can do something like:

awk '{system("kill -9 " $0)}' file

[theNbomr]

I think what you are trying to ask is how to iteratively take input from a file, and use the new data as part of a command for each iteration. To use your example, it can be done something like this (untested):

#
#  file 'pidfile' contains a list of process IDs to kill
#
while read pid; do
    echo "Killing $pid"
   # kill -9 $pid
done < pidfile

This script loops, reading a new record from pdifile on each iteration, and uses the value read as part of the command(s) executed within the loop.

There is nothing generically wrong with using backticks, although your example is a poor way to use them, as it will give an arbitrarily long argument list to the kill command. In this case, I think that is okay, but many commands like their argument list to be a single item, in which case your example will fail. Modern bash versions now use (prefer) the notation, $( conmmand ), to replace the use of backticks (which would otherwise be `command`).

--- rod.