Shell Programming and Scripting

Hi All,

I came across a bit of code that seems to work, even though I didn't expect it to (now that's wierd!)

#!/bin/sh
set -x
nn=15
if [ nn -eq 15 ]
then
echo "is true"
fi

The above code ends up comparing the string "nn" to number 15, but still evaluates to true. Here's the output when i run it :

+ nn=15
+ [ nn -eq 15 ]
+ echo is true
is true


while with [ "$nn" -eq 15 ], I get:

+ nn=15
+ [ 15 -eq 15 ]
+ echo is true
is true

which is what I expect.

By the way, if you assign nn=25 and run test nn -eq 15, it evaluates to false.

Any Ideas how the integer comparison is working without dereferencing the variable?

btw i m using AIX with sh
a friend informs me that apparently the code

nn=15
if [ nn -eq 15 ]

evaluates to false on solaris 8/sh