KSH For Loop Array: Iterate Through Array Values

Author: Vivek Gite Last updated: June 19, 2015 7 comments

How do I use ksh for loop to iterate thought array values under a UNIX / Linux / BSD operating systems?

The ksh shell supports two types of arrays:

Tutorial details
Difficulty	Easy (rss)
Root privileges	No
Requirements	Ksh
Time	5m

Syntax

You can define array as follows either as an associative array or to be an indexed array.

Syntax for an indexed array

arrayName[0]=value1
arrayName[1]=value2
arrayName[3]=value3

OR use set command as follows:

set -A arrayName value1 value2 value3

Syntax for an associative array

typeset -A employees
employees[sirname]="value1"
employees[firstname]="value"

set -A arrayName val1 val2 val3

Examples for ksh indexed array

For example, create an array called characters with three values as follows:

set -A characters Mugen Jin Fuu

To print first value, enter:

echo ${characters[0]}

To print 3rd and last value, enter:

echo ${characters[2]}

To print all values, enter:

echo ${characters[@]}

To count number of items in an array called characters, enter:

echo ${#characters[@]}

You can use for loop as follows to iterate through all values:

for i in ${characters[@]}; do echo "Samurai Champloo character - $i"; done

Sample outputs:

Samurai Champloo character - Mugen
Samurai Champloo character - Jin
Samurai Champloo character - Fuu

You can add two more items as follows to exiting array:

characters[3]="Sunflower-Samurai"
characters[4]="Detective-Manzo"

Sample Shell Script

#!/bin/ksh
# set array called nameservers
set -A nameservers 192.168.1.1 192.168.1.5 202.54.1.5
 
# print all name servers
for i in ${nameservers[@]}
do
	echo $i
done

Sample outputs:

Fig.01: Ksh for loop array ns demo

Ksh associative arrays examples

## set associative array ##
typeset -A ns 
 
## Add values ##
ns[home]="192.168.1.254" ## home dns server ip 
ns[isp]="123.1.2.254"    ## my isp dns server ip
ns[google]="8.8.8.8"     ## google public dns server ip
 
## Okay, display values #
print "${ns[home]}"
print "${ns[isp]}"
print "${ns[google]}"
 
## Count  number of items in an array #
print "${!ns[@]}"
 
## Use for loop to print all items in an array##
for i in "${!ns[@]}"
do
   echo "ns[$i] value is ${ns[$i]}"
done

Sample outputs:

ns[google] value is 8.8.8.8
ns[home] value is 192.168.1.254
ns[isp] value is 123.1.2.254

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