Linux Shell Scripting Cookbook - Third Edition

Passing an external variable to awk

Using the -v argument, we can pass external values other than stdin to awk, as follows:

    $ VAR=10000
    $ echo | awk -v VARIABLE=$VAR '{ print VARIABLE }'
    10000

There is a flexible alternate method to pass many variable values from outside awk. Consider the following example:

    $ var1="Variable1" ; var2="Variable2"
    $ echo | awk '{ print v1,v2 }' v1=$var1 v2=$var2
    Variable1 Variable2

When an input is given through a file rather than standard input, use the following command:

    $ awk '{ print v1,v2 }' v1=$var1 v2=$var2 filename

In the preceding method, variables are specified as key-value pairs, separated by a space, and (v1=$var1 v2=$var2 ) as command arguments to awk soon after the BEGIN, { }, and END ...