string manipulation in BASH

[ovince]

Hi All,

I would like to extract numbers 5, 15, 35 from filenames like (the second number in name):

join5x_angle_box5_tri.dat
join5x_angle_box15_tri.dat
join5x_angle_box35_tri.dat
....

How to do this?

I was thinking to apply command like


`expr index "$fileName" '.*box.*'`


in a loop, but it gives me back wrong position of the first number (2). What I do wrong here?

Thanks
oliver

 

[feherke]

Hi

[tt]expr index[/tt] does not search for substring, but for set of characters. So it does not return the starting position of "box" but the first position of any letter from the "b", "o", "x" set.

expr match "$fileName" '.*box'

Feherke.

http://rootshell.be/~feherke/

 

[ovince]

thanks.

this works
expr match "$fileName" '.*box'


but how come that
expr match "$fileName" '.*_tri'

does not find the position of '_'(ie the position of the end of the number)?

o.

 

[feherke]

Hi

You wrote that you want the number. Then why not :

nr=${fileName#*box}
nr=${nr%_*}

Feherke.

http://rootshell.be/~feherke/

 

[PHV]

And if you insist on expr:
`expr "$filename" : '.*box\([0-9]*\)_tri*'`

Hope This Helps, PH.
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