Question

Why does this work:

This

var=hello
myvar=`echo hello hi | awk "{ if (\\\$1 == \"$var\" ) print \\\$2; }"`
echo $myvar

gives

hi

But this does not?

This

var=hello
echo hello hi | awk "{ if (\\\$1 == \"$var\" ) print \\\$2; }"

gives

awk: cmd. line:1: Unexpected token

I am using

GNU bash, version 4.1.5(1)-release (i486-pc-linux-gnu)

on

Linux 2.6.32-34-generic-pae #77-Ubuntu SMP Tue Sep 13 21:16:18 UTC 2011 i686 GNU/Linux

Answer 1

If your awk is like mine, it will tell you where it fails:

var=hello
echo hello hi | awk "{ if (\\\$1 == \"$var\" ) print \\\$2; }"

awk: syntax error at source line 1
 context is
    { if >>>  (\ <<< $1 == "hello" ) print \$2; }
awk: illegal statement at source line 1

furthermore, if you replace awk by echo you’ll see clearly why it fails

echo hello hi | echo "{ if (\\\$1 == \"$var\" ) print \\\$2; }"
{ if (\$1 == "hello" ) print \$2; }

there are extra ‘\’ (backslashes) in the resulting command. This is because you removed the backquotes.
So the solutions is to remove a pair of \’s

echo hello hi | awk "{ if (\$1 == \"$var\" ) print \$2; }"
hi