Les Mikesell <lesmikesell@xxxxxxxxx> wrote:
aragonx@xxxxxxxxxx wrote:
> I bet awk has it's own user list but before I go and subscribe to another
> one, I figured I would ask here first. I have the following awk code that
> is trying to set a variable of the shell it is running in. It doesn't
> work and I've searched high and low to see how to get it to do so.
>
> The reason I don't just use DOMAIN= 'awk blah blah blah' is I want to set
> more than one shell variable for each record. But I have to get this
> working first. :(
>
> #!/bin/bash
>
> awk '{FS=":"}{system ("DOMAIN=" $1); }
> {system ("DOMAIN="$1)};
> {system ("echo \"$DOMAIN\"")};
> ' /etc/passwd
>
> Any help would be appreciated.
This isn't an awk question, it's a 'how unix works' question. A child
process can't change anything in it's parent's environment. Your awk
program will be a child of the shell running it; the system statements
run yet another shell as a child under awk. All of those processes have
their environment strings in protected memory (inherited shared but
copy-on-write).
The var=`command ..` will work, or you can do all of the work that needs
the setting in the lowest level subprocess that has the right values.
-- Les Mikesell lesmikesell@xxxxxxxxx
An alternative is to have the awk script output the shell commands you
want. That is, change your {system ("DOMAIN="...} to a print
statement. You then execute the command created by your awk script in
the calling shell's environment. Something along the lines of:
foo = `awk '{FS=":"}{printf "export DOMAIN=%s\n", $1}' < /etc/passwd`
`echo $foo`
After the above, $DOMAIN should have the value you want for the *last
entry* in /etc/passwd. Not sure if this is what you really want. That
may be:
foo=`awk 'BEGIN {FS=":"} $1 ~ /'$USER'/ {printf "export DOMAIN=%s\n",
$1}' /etc/passwd`
`echo $foo`
You'll find understanding quoting and order of execution is really
useful when writing this kind of shell script. ;-)
Cheers,
Dave
--
Politics, n. Strife of interests masquerading as a contest of principles.
-- Ambrose Bierce