markdo
January 3, 2012, 5:26pm
1
Hi, I have a question
thanks
Lookup bash parameter expansion. Here is a url:
BashFAQ/083 - Greg's Wiki
# Bourne test "${var+defined}"
This expansion results in nothing if var is undefined. Therefore test returns false. If var is defined (to either "" or something longer), the expansion returns "defined", and therefore test returns true. You could use any non-empty string in place of "defined", but readability is always nice.
methyl
January 3, 2012, 8:21pm
3
The string test is avoiding a syntax error if the environment variable ${lt_cv_path_SED} is blank. It's too easy to write code which the next person cannot follow.
Imho it would be better as:
if test "${lt_cv_path_SED+set}" = "set"; then
Or even better as:
if [ "${lt_cv_path_SED}""set" = "set" ]; then
