On Sat, May 05, 2001 at 02:34:47PM -0700, Karsten M. Self wrote: > > In contrast, csh and derivatives have: > > $?MYVAR > > ...which allows testing of presence of a variable. > > ...but I'm not aware of a similar bash/korn/bourne feature. Anyone? Coming soon to ./configure scripts near you: if test "${LANG+set}" = set; then LANG=C; export LANG; fi or in your case: if test "${MYVAR+set}" = set; then echo "MYVAR doesn't exist" else echo "MYVAR exists, value: $MYVAR" fi also available in bash(1): In each of the cases below, word is subject to tilde expansion, parameter expansion, command substitution, and arithmetic expansion. When not performing substring expansion, bash tests for a parameter that is unset or null; omitting the colon results in a test only for a parameter that is unset. ${parameter:+word} Use Alternate Value. If parameter is null or unset, nothing is substituted, otherwise the expan sion of word is substituted. Since it is used in configure scripts, I'd guess it's pretty portable. -- Tommi Komulainen Tommi.Komulainen@iki.fi GPG 1024D/68388EE6 6FD6 DD79 EB38 BF6F 3533 09C0 04A8 9871 6838 8EE6
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