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Top Forums Shell Programming and Scripting How to implement "not in" logic in UNIX script? Post 302885577 by alister on Monday 27th of January 2014 11:52:10 AM
Old 01-27-2014
Quote:
Originally Posted by Akshay Hegde
Code:
$ if ! grep Feb Jan.txt >/dev/null; then echo "yes"; else echo "No"; fi
yes

Instead of redirecting to /dev/null, consider using grep -q. -q tells grep that you are only interested in the exit status, so if a match is found grep can exit immediately, avoiding unnecessary i/o.

Regards,
Alister
 

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script(1)							   User Commands							 script(1)

NAME
script - make record of a terminal session SYNOPSIS
script [-a] [filename] DESCRIPTION
The script utility makes a record of everything printed on your screen. The record is written to filename. If no file name is given, the record is saved in the file typescript. See WARNINGS. The script command forks and creates a sub-shell, according to the value of $SHELL, and records the text from this session. The script ends when the forked shell exits or when Control-d is typed. OPTIONS
The following option is supported: -a Appends the session record to filename, rather than overwriting it. NOTES
script places everything that appears on the screen in filename, including prompts. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWcsu | +-----------------------------+-----------------------------+ |CSI |Enabled | +-----------------------------+-----------------------------+ SEE ALSO
attributes(5) WARNINGS
script can pose a security risk when used in directories that are writable by other users (for example, /tmp), especially when run by a privileged user, that is, root. Be sure that typescript is not a link before running script. SunOS 5.11 30 Jan 2004 script(1)
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