Detecting failure of a Bash "export" value

bash, scripting

Solution

var=`svn ls`
if [[ $? == 0 ]]
then
        export var
else
        unset var
fi

`$?` is the exit code of the last command executed, which is `svn ls` here.

jmohr's solution is short and sweet. Adapted mildly,

var=`svn ls` && export var || unset var

would be approximately equivalent to the above (`export` of a valid identifier will never fail, unless you've done something horrible and run out of environment space). Take whatever you want -- I use `unset` just to avoid `$var` possibly having a value even though it's not exported.

Problem

In Bash I'm executing a command and putting the result in a variable like this: ``` export var=`svn ls` ``` But if SVN fails for some reason--say it returns a non-zero error code--export still returns status code 0. How do I detect if the executed command fails?

Original source