Programming Forums - A simple script to execute a command package

Programming Forums (http://www.programmingforums.org/forumindex.php)

- Bash / Shell Scripting (http://www.programmingforums.org/forum26.html)

- - A simple script to execute a command package (http://www.programmingforums.org/showthread.php?t=5328)

A simple script to execute a command package

Hi folks,

I'm prepared to write a simple script to execute 20+ commands and could not figure out how to make use of "loop" subject to certain conditions.

If without conditions

#!/bin/bash



cmd1="code1" #the exact/full command

cmd2="code2" #the exact/full command

cmd3="code3" #the exact/full command

etc.



     cmd1 || exit 1

     cmd2 || exit 2

     cmd3 || exit 3

     ...

     cmdn || exit n

     echo "Build environment entered!"

exit 0

It will be a long script. Please advise how to apply "loop" to shorter the script executing all command subject to following conditions

1) All commands except cmd3 should have no output. If there is any it needs to confirm either to continue OR to exit the shell

2) cmd3 should have "/mnt/lfs" output. If no output OR empty output the shell should exit, not continue executing further commands

TIA

satimis

Not really sure what you're going for here, but the number of lines required to initialize 20 variables and loop through them is greater than the number of lines required to simply list 20 commands... maybe I'm missing something :confused:

I'm guessing, from the wording ("full/exact command") that the idea is that the commands stored in the variables can be edited to adjust the behaviour of the script (kind of like setting CFLAGS etc. in a makefile).

I'm not a great bash guru, but it sounds like what you would really benefit from is a small subroutine (one that executes the command, checks for any output, and prompts as necessary). If you need information about functions, see http://www.tldp.org/HOWTO/Bash-Prog-Intro-HOWTO-8.html or the bash manpage.

You could also use a loop to iterate over your values, but not if they're in simple scalar variables. Bash does support arrays, though (http://www.faqs.org/docs/bashman/bashref_71.html); you could loop over the array quite easily with a C-style for loop (http://www.tldp.org/LDP/abs/html/loops1.html introduces looping).

I'm not exactly a bash expert myself, as I say, but hopefully that helps you.

Hi folks,

Tks for your advice. Sorry for not posting more detail on my 1st message.

I'm prepared to write a simple shell scripts executing following commands automatically.

There are 25 commands to be executed in following sequence

export LFS=/mnt/lfs

mount /dev/hda6 /mnt/lfs

mkdir -p $LFS

echo $LFS

/mnt/lfs (output)

/usr/sbin/chroot "$LFS" /tools/bin/env -i HOME=/root TERM="$TERM" PS1='\u:\w\$ '     PATH=/bin:/usr/bin:/sbin:/usr/sbin:/tools/bin /tools/bin/bash --login +h

mknod -m 600 /dev/console c 5 1

mknod -m 666 /dev/null c 1 3

mount -n -t tmpfs none /dev

mknod -m 622 /dev/console c 5 1

mknod -m 666 /dev/null c 1 3

mknod -m 666 /dev/zero c 1 5

mknod -m 666 /dev/ptmx c 5 2

mknod -m 666 /dev/tty c 5 0

mknod -m 444 /dev/random c 1 8

mknod -m 444 /dev/urandom c 1 9

chown root:tty /dev/{console,ptmx,tty}

ln -s /proc/self/fd /dev/fd

ln -s /proc/self/fd/0 /dev/stdin

ln -s /proc/self/fd/1 /dev/stdout

ln -s /proc/self/fd/2 /dev/stderr

ln -s /proc/kcore /dev/core

mkdir /dev/pts

mkdir /dev/shm

mount -t devpts -o gid=4,mode=620 none /dev/pts

mount -t tmpfs none /dev/shm

In normal circumstance there is no output on all commands except command-4 with "/mnt/lfs" as output. If not considering the output it will be quite simple just listing all commands on a shell script.

Now I expect to arrange the script as follows;
1) The script will automatically continue to execute command-5 if the output of command-4 is "/mnt/lfs" satisfying the condistion otherwise exit the shell.
2) If there is an output on any command excluding command-4 it needs to confirm "yes/no" with the corresponding command displayed on the terminal. 'yes" will continue on next command. "no" will exit the shell stopping the script.

I'm considering whether shell script or perl script will do the job better. If shell script then how to start. If perl script then how to start. Which module/modules will be appropriate to apply, TIA

B.R.
satimis