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Full Discussion: How do I perform double substitution in bash?
Top Forums Shell Programming and Scripting How do I perform double substitution in bash? Post 302305709 by flee on Thursday 9th of April 2009 02:26:12 PM
Old 04-09-2009
How do I perform double substitution in bash?
Code:
#!/bin/bash
#set -x
MAX=255
FILE=$1.dns_list
#declare -a d_arr

if [ -z "$1" ]
then
          echo "Usage: `basename $0` network"
          echo "  e.g.`basename $0` 1.1.1"
          exit 
fi

echo "Remove file $FILE..."
rm $FILE

for (( i = 1; i < $MAX; i++ ))
do
    PARSE=$(host $1.${i})
        if [ $? = 0 ]
          then
             echo "$PARSE" " $1.$i" >> $FILE
        fi
done

cat $FILE | while read i
do
declare -a d_arr
ln=`echo $i | awk '{printf $5 "\t : \t" $6}' |sed 's/\.XYZ\.com\.//g'`
cnt=${#d_arr[@]}
let c=$cnt
d_arr[$c]=$ln       # <<---<<  I think I need double substitution for this stmt
echo ${d_arr[$c]}
done

# For some reason the array does not exist 
cnt1=${#d_arr[@]}
echo "The size of d_arr: $cnt1"
echo "The array ${d_arr[@]}"
exit

Hi,

How do I perform double substitution in bash?

I try to write a bash script to list all the DNS entry from a subnet e.g. 192.168.1.0/24 and store the valid DNS entry into an array ${d_arr[]},
The variable d_arr[$c] works fine in while read i loop, but once the loop finished, array ${d_arr[]} is empty, I have tried he following:

Code:
let ${d_arr[$c]}=$ln

but get a syntax error.

How do I get it store into an array for the duration when he program is still running?

Thanks,
-Fu
Last edited by rbatte1; 12-13-2016 at 09:44 AM.. Reason: Added CODE tags
 

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LEARN ABOUT OPENSOLARIS

noecho

echo(3XCURSES)						  X/Open Curses Library Functions					    echo(3XCURSES)

NAME

       echo, noecho - enable/disable terminal echo

SYNOPSIS

       cc [ flag... ] file... -I /usr/xpg4/include  -L	/usr/xpg4/lib 
	-R  /usr/xpg4/lib  -lcurses  [ library... ]

       c89 [ flag... ] file... -lcurses [ library... ]

       #include <curses.h>

       int echo(void);

       int noecho(void);

DESCRIPTION

       The  echo()  function enables Echo mode for the current screen. The noecho() function disables Echo mode for the current screen. Initially,
       curses software echo mode is enabled and hardware echo mode of the tty driver is disabled. The echo() and noecho() functions control  soft-
       ware echo only. Hardware echo must remain disabled for the duration of the application, else the behavior is undefined.

RETURN VALUES

       Upon successful completion, these functions return OK. Otherwise, they return ERR.

ERRORS

       No errors are defined.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Unsafe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       getch(3XCURSES), getstr(3XCURSES), initscr(3XCURSES), libcurses(3XCURSES), scanw(3XCURSES), attributes(5), standards(5)

SunOS 5.11							    5 Jun 2002							    echo(3XCURSES)
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