Setting an environment variable from awk output within a shell script?

[fusi0n]

Hi! I'm reasonably new to awk and shell scripting, and am having difficulties with getting my shell script to set an environment variable based on the awk output from within a shell. I need to be able to reset the variable for each pass of a loop.

Basically, I fetch the name from a file using
awk 'NR==2' R0-results.mol2
And I need to be able to use this output to set the variable mol2file within my shell script run within csh.

I have tried:
awk 'NR==2 {print "set mol2file=" $0}' R0-results.mol2 | sh
and
awk 'NR==2 {print "set mol2file=" $0}' R0-results.mol2

as well as a few other variations that were erased, but all commands will generate the correct command when run at the command line:

set mol2file=pp_5_188_000

which then sets the variable when run as echoed as above. However, I cannot get it to invoke the set variabel command from within the shell script.

I also tried used a system call function:

awk 'NR==2 {system("set filsname=" $0)}' R0-results.mol2

But again, it has the correct command when echoed, but will not be invoked from within the shell script.

What am I doing wrong? How do I invoke a set variable command from within a shell script based on my awk output?

Any help is greatly appreciated!
Thanks!

 

[KenCunningham]

I'm probably misunderstanding this but does your shell support export variable=value?

I don't mind people who aren't what they seem. I just wish they'd make their mind up.

 

[fusi0n]

Unfortunately, it doesn't

 

[Annihilannic]

Have you tried:

[tt]eval `awk 'NR==2 {print "set mol2file=" $0}' R0-results.mol2`[/tt]

Or simpler actually:

[tt]set mol2file=`awk 'NR==2' R0-results.mol2`[/tt]

Annihilannic.

 

[fusi0n]

I hadn't tried the eval version.

Both of them, when run from the command line, will set the variable correctly. However, when I put either one in a shell script and run it, it still doesn't set the variable, claiming it to be undefined when I try to echo it afterwards.

 

[Annihilannic]

You can't set a variable in your current (parent) shell by running another (child) shell script. The only way you can 'run' a script to set variables in the current shell is with the . or source (for C shell) prefix, e.g.

[tt]. /some/scriptname
source /some/scriptname[/tt]

Annihilannic.

 

[fusi0n]

Well, that would sure explain why I couldn't get anything to work prior!

That fixes the biggest problem I was having (which are usually the silliest ones).

Thanks so much!!