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Top Forums Shell Programming and Scripting Handling null Integer/string variables Post 302604712 by alister on Monday 5th of March 2012 06:45:46 PM
Old 03-05-2012
Quote:
Originally Posted by gary_w
Also eliminate the grep -v grep and save a process by doing this:
Code:
LAN_VARIABLE=$(ps -ef | grep [m]intty | awk '{print $2}')

Matches the string "mintty" but not itself, thus eliminating the need to grep -v grep..
[m]intty is both a valid regular expression for grep and a valid sh pattern for pathname expansion. If you don't quote that argument, and if the current working directory has a matching item, the pathname expansion would consume the brackets before grep is exec'd. The pipeline could give an erroneous result if its grep is listed in ps' output.

Obviously, what I just pointed out is not likely to happen, but it's not impossible. I mention it merely for thoroughness.

Regards,
Alister
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shell(1F)							   FMLI Commands							 shell(1F)

NAME
shell - run a command using shell SYNOPSIS
shell command [command] ... DESCRIPTION
The shell function concatenate its arguments, separating each by a space, and passes this string to the shell ($SHELL if set, otherwise /usr/bin/sh). EXAMPLES
Example 1: A sample output of shell command. Since the Form and Menu Language does not directly support background processing, the shell function can be used instead. `shell "build prog > /dev/null &"` If you want the user to continue to be able to interact with the application while the background job is running, the output of an exe- cutable run by shell in the background must be redirected: to a file if you want to save the output, or to /dev/null if you don't want to save it (or if there is no output), otherwise your application may appear to be hung until the background job finishes processing. shell can also be used to execute a command that has the same name as an FMLI built-in function. NOTES
The arguments to shell will be concatenate using spaces, which may or may not do what is expected. The variables set in local environments will not be expanded by the shell because "local" means "local to the current process." ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWcsu | +-----------------------------+-----------------------------+ SEE ALSO
sh(1), attributes(5) SunOS 5.10 5 Jul 1990 shell(1F)
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