splitting variables In Bash Programming

neorion · 08-04-2004, 11:15 AM

Hello,
I am a writing a program which has a variable defined to a list of numbers seperated by spaces. I wish to make each number in that initial variable each their own variables. The ammounts of numbers may not always be the same so sometimes there might be 10 numbers in the initial string I have experimented with awk but i dont even know if i am going in the right direction with that . Any help is really appreciated... Thanks
-NeorioN

jim mcnamara · 08-04-2004, 03:44 PM

Try using arrays -- here is a ksh example:

Code:

#!/bin/ksh  
# arrays
myarray=''               
# build an array
to_array ()
{
  unset myarray
  set -A myarray `echo $*`
}                 

# display an array                                     
disp_array () {
let i=0
while (( i < ${#myarray[*]} )) ; do
   echo "array element $i = ${myarray[i]} "
   let i=i+1
done
}                  

#demo of arrays

a="10 13 12 9"
b="1 2 3 4 5 6 7 8 9 10"  
to_array "$a" 
echo "array created from: $a"
disp_array
to_array "$b"               
echo "array created from: $b"
disp_array

exit

Hko · 08-04-2004, 05:28 PM

In bash it's quite easy. Just execute the "set" command with you list-variable. You can then acces them with $1, $2, $3, ... or iterate through them using the "shift" command. Of course the original contents of $1, $2,... (the script arguments) are lost. But you can save them before in seperate var's, or in just one var, e.g: SAVED_ARGS=$* and then restore the arguments with "set $SAVED_ARGS" later on.

Demo:

Code:

#!/bin/bash

# We are going to lose the arguments passed to the this
# script. So store them in other var's before.

LIST="3 76 23 22 345 22 1 9 8 6  3  3     3 2 2  1"

# Set the items in the postitional parameters ($1, $2, $3, ...)
# If the list is comma-seperated, you need to set the IFS var to a comma
# before the set command. E.g:  IFS=,

set $LIST

# Now the original argument to the script have disappeared.
# They have been replaced by the items from $LIST

echo $1
echo $2
echo $3
echo $4
echo $5
echo $6
echo $7
echo $8
echo $9
echo ${10}  # When you need two digits, curly braces are needed.
echo ${11}
echo ${12}
echo ${13}
echo ${14}
echo ${15}
echo ${16}
echo ${17}

echo ==============================

# Or you can iterate through them, with shift.
# After a shift:
#   $1 becomes $2
#   $2 becomes $3
#   ...and so on.  ($0 is not touched by shift)

echo $1
while shift ; do
	echo $1
done