Array

List of Topics

1) What is array
2) Options with Array

1) What is Array

2) Syntax of Array

Name [index] = value

Where,

Name - Is any name for an array

Index could be any number or expression that must evaluate to a number greater than or equal to zero.You can declare an explicit array using declare -a arrayname.

If the elements has the white space character, enclose it with in a quotes.

3) Syntax of Array

declare -a Unix=('Debian' 'Red hat' 'Suse' 'Fedora');

declare -a arrayn=(element1 element2 element3)

echo ${arrayn[1]}

In bash, array is created automatically when a variable is used in the format like,

There are different ways to print the whole elements of the array. If the index number is @ or *, all members of an array are referenced. You can traverse through the array elements and print it, using looping statements in bash.

4) Other options with the array

a) To find length of the Array

echo ${#arrayname[@]} 
echo ${#arrayname[Index]} 


[user@Server ~]$ cat a.sh
#! /bin/bash
## Start of Script
Unix[0]='Debian'
Unix[1]='Red hat'
Unix[2]='Ubuntu'
Unix[3]='Suse Linux'

echo ${#Unix}  #Number of characters in the first element of the array.i.e Debian

echo ${#Unix[3]}
echo ${#Unix[@]}

##End of Script
[user@Server ~]$ sh a.sh
6
10

4

14. Deleting an Entire Array

unset is used to delete an entire array.

$cat arraymanip.sh

#!/bin/bash

Unix=('Debian' 'Red hat' 'Ubuntu' 'Suse' 'Fedora' 'UTS' 'OpenLinux');

Shell=('bash' 'csh' 'jsh' 'rsh' 'ksh' 'rc' 'tcsh');

UnixShell=("${Unix[@]}" "${Shell[@]}")

unset UnixShell

echo ${#UnixShell[@]}

$ ./arraymanip.sh

0

regex[1]="line1\|here1"

regex[2]="line2\|here2"

regex[3]="line3\|here3"

regex[4]="line4\|here4"

for i in "${!regex[@]}"

do

        grep -h -r --color=always "${regex["$i"]}" file.txt >> "pattern$i.txt"

done

#!/bin/bash

array=(un1Z1269E9909 rb1Z129098515)

echo ${array[0]:0:2}

echo ${array[1]:0:2}

three=${(array[3]:0:2):=word}

echo $three

var="$1"

var=${var:=word}

echo "$var"