How do i get numbers from a string?

eliraza6 · #1 (**permalink**) 07-18-2007

Hi...
I'm new here and i have a Q...

How do i get only the number from a string?
like from "rlvol11" i want to get 11
or from "lvol4" i want to get 4

what commands should i use at my script?

thanx 4 the help!

Eliraz.

lorcan · #2 (**permalink**) 07-18-2007

in ksh/bash

Code:

echo $variable |  tr -d '[A-Za-z]' | read numStr

Example

Code:

echo "lvol4" |  tr -d '[A-Za-z]' | read numStr
echo $numStr

vino · #3 (**permalink**) 07-18-2007

One way is

Code:

echo "rlvol11" | tr -d '[:alpha:]'

See man tr for more details.

radoulov · #4 (**permalink**) 07-18-2007

With bash:

Code:

$ v="rlvol11";echo "${v//[!0-9]}"
11

bigearsbilly · #5 (**permalink**) 07-18-2007

better:

tr -dc '[0-9]'

eliraza6 · #6 (**permalink**) 07-18-2007

First of all thanx!
it worked but i still have a problem with my script...
i want to make a script that gets a VG name and outputs the size of it's lvols...

here is what i wrote but it doesn't work...

Code:

for x in *
    do
        if [ "echo $x" = "lvol*" ]; then
    echo $x |  tr -d '[A-Za-z]' | read lvolnum
    echo /dev/$1/lvol$lvolnum
    lvdisplay lvol${lvolnum} | grep Mbytes
        fi
done

can someone please help me?
thanx alot!

vino · #7 (**permalink**) 07-18-2007

Quote:

Originally Posted by eliraza6

Code:

for x in *
    do
        if [ "echo $x" = "lvol*" ]; then
    echo $x |  tr -d '[A-Za-z]' | read lvolnum
    echo /dev/$1/lvol$lvolnum
    lvdisplay lvol${lvolnum} | grep Mbytes
        fi
done

Code:

for x in *
do
      if [ "$x" = lvol* ]; then
        echo $x |  tr -d '[A-Za-z]' | read lvolnum
        echo /dev/$1/lvol${lvolnum} --> Where did you get $1 from ?
        lvdisplay lvol${lvolnum} | grep Mbytes
      fi
done

I have a feeling it all boils down to just

Code:

for x in lvol*
do
  echo /dev/$1/$x
  lvdisplay $x | grep MBytes
done

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