Shell Programming and Scripting

Shell Scripting Gurus,
I am having a hard time trying to figure out what I am doing wrong in my script. Below is the script snippet. It gives an error when it tries to execute the expression.

a=`expr substr $stringZ 5 10`


#!/bin/bash
echo "Hello"
stringZ="abcABC123ABCabc"
echo $stringZ
echo "Length is ${#stringZ}"
echo `expr "$stringZ" : '.*'`
a=`expr substr $stringZ 5 10`
echo $a

output :

Hello
abcABC123ABCabc
Length is 15
15
expr: syntax error
$


What am I doing wrong? Why is it giving syntax error when it executes
a=`expr substr $stringZ 5 10`

Can one of you gurus out there help me fix this?

Thanks a lot!
Ajay.

Dunno why you get the syntax error from expr, but you could use bash's builtin substring facility.

Code:

a=${stringZ:5:10}

I think this should rather have been addressed by era,
the herder of Randal's useless use of cat awards?
I would here say, contender for useless use of echo and backticks award
But I noticed one difference.
The nifty bash substr expansion seems to start counting chars from naught
(which seems logical to programmers)
whereas the expr substr seems indexing from 1 (which I would say is more Fortran style, if I remember correctly)

Code:

$ str=abcABC123ABCabc
$ echo ${str:5:10}
C123ABCabc
$ expr substr $str 5 10
BC123ABCab

Era and Buffoonix,

Thanks a lot! Your inputs helped me in fixing my problem.