expr command

Shell Programming and Scripting
1

Hi
Can anyone explain me the usage of this command and the arguments used here and what will be the expected output :

v_num=`expr nav_d_20100204_1759 : '[^(0-9)]*\([0-9]*\)'`

what will be the value returned in v_num.

Thanks in Advance!!!

Regards
Naveen Purbia

2

Number matched by this pattern \([0-9]*\) is the output

Why dont you run the command and see the output?

3

i run and got output as : 20100204 only.
why other numbers were ignored ?

4

Change the pattern to

expr nav_d_20100204_1759 : '[^(0-9)]*\([0-9]*_[0-9]*\)'