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Top Forums Shell Programming and Scripting Adding an element to a bash array with a variable Post 302937958 by LMHmedchem on Wednesday 11th of March 2015 01:39:25 AM
Old 03-11-2015
Quote:
Originally Posted by Chubler_XL
This seems to be working fine for me:

Code:
$ CMD_STRING='-L 22 -s 0 -r -O -A i -N 100 -n'
$ CMD_STRING_LIST=(1 2 3)
$ CMD_STRING_LIST=("${CMD_STRING_LIST[@]}" "$CMD_STRING")
$ echo ${#CMD_STRING_LIST[@]}
4
$ echo ${CMD_STRING_LIST[3]}
-L 22 -s 0 -r -O -A i -N 100 -n

I wonder if your doing this all within a loop and loosing the changes due to Bash sub-shell: variables lost
Yes it is in a loop. I am trying to accumulate a list of commands to run later.

The post you linked to is interesting. I am sure I have done this kind of thing before, meaning accumulated data in an array from inside a loop. A loop is the most likely place where you would want to push allot of data into a structure. I do remember having some issues with the syntax before since I don't do it very often, but I don't remember it not working. Perhaps it matters where the array is declared. Is this like c++ where a variable declared in {} will not be in scope outside of the {}?

I will try to look for some other scripts where I have this method working.

LMHmedchem
 

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LOSETUP(8)						       MAINTENANCE COMMANDS							LOSETUP(8)

NAME
losetup - set up and control loop devices SYNOPSIS
losetup [ -e encryption ] [ -o offset ] loop_device file losetup [ -d ] loop_device DESCRIPTION
losetup is used to associate loop devices with regular files or block devices, to detach loop devices and to query the status of a loop device. If only the loop_device argument is given, the status of the corresponding loop device is shown. OPTIONS
-d detach the file or device associated with the specified loop device. -e encryption enable data encryption. The following keywords are recognized: NONE use no encryption (default). XOR use a simple XOR encryption. DES use DES encryption. DES encryption is only available if the optional DES package has been added to the kernel. DES encryption uses an additional start value that is used to protect passwords against dictionary attacks. -o offset the data start is moved offset bytes into the specified file or device. RETURN VALUE
losetup returns 0 on success, nonzero on failure. When losetup displays the status of a loop device, it returns 1 if the device is not con- figured and 2 if an error occurred which prevented losetup from determining the status of the device. FILES
/dev/loop0,/dev/loop1,... loop devices (major=7) EXAMPLE
If you are using the loadable module you must have the module loaded first with the command # insmod loop.o The following commands can be used as an example of using the loop device. dd if=/dev/zero of=/file bs=1k count=100 losetup -e des /dev/loop0 /file Password: Init (up to 16 hex digits): mkfs -t ext2 /dev/loop0 100 mount -t ext2 /dev/loop0 /mnt ... umount /dev/loop0 losetup -d /dev/loop0 If you are using the loadable module you may remove the module with the command # rmmod loop RESTRICTION
DES encryption is painfully slow. On the other hand, XOR is terribly weak. AUTHORS
Original version: Theodore Ts'o <tytso@athena.mit.edu> Original DES by: Eric Young <eay@psych.psy.uq.oz.au> Linux Nov 24 1993 LOSETUP(8)
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