Shell Programming and Scripting

[~/temp]$ cat esham.txt 
[ath0]
ESSID=open
MODE=managed
[ath1]
ESSID=wep
MODE=wep

[~/temp]$ cat esham.ksh 
#! /bin/ksh

sed -n -e '/\[ath[0-9]\]/{
N
s#ESSID=\(.*\)#\1#p
}' esham.txt

[~/temp]$ ./esham.ksh
[ath0]
open
[ath1]
wep
[~/temp]$

[~/temp]$ cat esham.ksh 
#! /bin/ksh

sed -n -e '/\[ath[0-9]\]/{
N
s#.*\(ath[0-9]\).*\nESSID=\(.*\)#\1=\2#p
}' esham.txt

[~/temp]$ ./esham.ksh 
ath0=open
ath1=wep

sed -n -e '/^\[.*]/{
N
s#^\[\(.*\)\]\nESSID=\(.*\)#\1=\2#p
}' esham.txt