Unix questions - Is there an "undo" for export at the end of a shell script?

Author

Is there an "undo" for export at the end of a shell script?

Ulf Meinhardt

2005-02-17, 5:54 pm

Assume I change an environment variable at the beginning of a shell script e.g.

export BLA=myval:$BLA

Notice that $BLA already exists and has an unknown content. How do I switch back
to the original value at the end of the shell execution?

At a first glance I could store the initial value in a local variable:

savebla=$BLA
export BLA=myval:$BLA
.....
....other manipulations of $BLA
.....
(*1)
.....
export BLA=$savebla
exit

But what happens if the shell crashes at (*1) ?
The env variable has no chance to get back its original value.

Ulf