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Full Discussion: Shell advanced syntax?
Top Forums Shell Programming and Scripting Shell advanced syntax? Post 302463829 by alister on Monday 18th of October 2010 02:21:16 PM
Old 10-18-2010
Quote:
Originally Posted by alt
because I am expecting no return from export command.
Every single command run on a UNIX/Linux/POSIX system will return an exit status. If that exit status is 0, the shell treats that as a boolean true. Any other exit status is treated as a boolean false.

Regards,
Alister

---------- Post updated at 02:21 PM ---------- Previous update was at 02:14 PM ----------

Quote:
Originally Posted by alister
That's close but not quite correct. The original version's echo executes if the export command fails. This interpretation's does not.

Regards,
Alister

Actually, export always returns a 0 exit status, so it will never fail. Scrutinizer's code should work just as the original.

That said, I'll leave my post as is since that's a very unusual corner case. In just about every other situation, a command can return a non-zero exit status and the constructs would not be logically equivalent.

Regards,
Alister
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xdriver(1grass) 						Grass User's Manual						   xdriver(1grass)

NAME
XDRIVER - GRASS Monitor - driver to display GRASS maps in X11 environment. (drivers) DESCRIPTION
The GRASS XDRIVER can be used to display GRASS maps in X11 environment. Usage in details Variables: GRASS_WIDTH set the x size in pixel for the XDRIVER (default: 640) GRASS_HEIGHT set the y size in pixel for the XDRIVER (default: 480) XDRIVER_TRUECOLOR=[TRUE|FALSE] Look for a TrueColor visual (?) XDRIVER_WINDOW ? XDRIVER_PRIVATE_CMAP Private color map (?) XDRIVER_LEFT defines the left position of GRASS monitor (removed?) XDRIVER_TOP define the upper position of GRASS monitor (removed?) Set the XDRIVER size # bash shell syntax: export GRASS_WIDTH=xxx export GRASS_HEIGHT=yyy # c shell syntax: setenv GRASS_WIDTH xxx setenv GRASS_HEIGHT yyy To control the XDRIVER, use the d.mon module. The maximum color depth depends on the current X Server settings. SEE ALSO
Display drivers HTMLMAP driver, PNG driver, PostScript driver d.frame, d.mon, g.region d.rast, d.vect AUTHORS
CERL various improvements from several authors. Rewritten 2001 by Glynn Clements Last changed: $Date: 2008-03-23 15:34:53 +0100 (Sun, 23 Mar 2008) $ Full index (C) 2003-2011 GRASS Development Team GRASS 6.4.2 xdriver(1grass)
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