Comments on: BASH shell scripting tip: Set default values for variable http://www.cyberciti.biz/tips/howto-setting-default-values-for-shell-variables.html This is a Linux sys admin journal by Vivek about sys admin work, Linux tips & tricks, hacks, news and more. Fri, 10 Feb 2012 20:37:43 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Vivek Gitehttp://www.cyberciti.biz/tips/howto-setting-default-values-for-shell-variables.html#comment-149928 Vivek Gite Sat, 08 Aug 2009 05:29:15 +0000 http://www.cyberciti.biz/tips/howto-setting-default-values-for-shell-variables.html#comment-149928 See <a href="http://www.cyberciti.biz/faq/bash-ksh-if-variable-is-not-defined-set-default-variable/" rel="nofollow">this FAQ</a>. See this FAQ.

]]> By: 0xceptionhttp://www.cyberciti.biz/tips/howto-setting-default-values-for-shell-variables.html#comment-149927 0xception Fri, 07 Aug 2009 23:23:42 +0000 http://www.cyberciti.biz/tips/howto-setting-default-values-for-shell-variables.html#comment-149927 Thanks for the explanation... I've been trying to work with some shell scripts which are a bit more advanced then what i'm used to and this helped a lot. I was wondering if you also knew what ${VAR:+xxx} syntax and/or the ${VAR:-xxx} is for? I'm seeing this in a script which uses export ${NO_EXPORT:+-n} CONFIG_SECTION="$name" is this just a method of applying an conditional flag to a variable inline (like an assert statement)? I'm not sure as if that were true they could just as simply do [ -n "$NO_EXPORT" ] && CONFIG_SECTION="$name" Thanks for the explanation… I’ve been trying to work with some shell scripts which are a bit more advanced then what i’m used to and this helped a lot. I was wondering if you also knew what ${VAR:+xxx} syntax and/or the ${VAR:-xxx} is for?

I’m seeing this in a script which uses
export ${NO_EXPORT:+-n} CONFIG_SECTION=”$name”

is this just a method of applying an conditional flag to a variable inline (like an assert statement)? I’m not sure as if that were true they could just as simply do
[ -n "$NO_EXPORT" ] && CONFIG_SECTION=”$name”

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