Bash shell Problem with let command in Ubuntu 10.04

[webusr1]

Can anyone help with getting the all Bash shell commands in Ubuntu 10.04 working. I'm taking a Linux OS class and now as I try to work on shell scripting I've discovered that the Bash shell in Ubuntu 10.04 doesn't recognize many commands. For example, the simple let command doesn't work, here's my terminal output and file contents.

file: testscr
etcmon@etcmon-laptop:~$ cat testscr
let x=100
echo $x


etcmon@etcmon-laptop:~$ sh testscr
testscr: 1: let: not found

Any HELP would .be greatly appreciated.

Thanks

[holiday]

Can anyone help with getting the all Bash shell commands in Ubuntu 10.04 working. I'm taking a Linux OS class and now as I try to work on shell scripting I've discovered that the Bash shell in Ubuntu 10.04 doesn't recognize many commands. For example, the simple let command doesn't work, here's my terminal output and file contents.

file: testscr
etcmon@etcmon-laptop:~$ cat testscr
let x=100
echo $x


etcmon@etcmon-laptop:~$ sh testscr
testscr: 1: let: not found

Any HELP would .be greatly appreciated.

Thanks

In Ubuntu, the /bin/sh link points to dash. So you will have to specify bash in your script.

#!/bin/bash
let x=100
echo $x

Make the file executable and run it.

$ chmod +x testscr
$ ./testscr

or

$ bash testscr

[shashanksingh]

use "bash" instead of "sh"

It'll work

[sisco311]

EDIT: I'm too slow. holiday and shashanksingh beat me to it. :)

In Ubuntu, the default system shell, /bin/sh, is dash (http://en.wikipedia.org/wiki/Debian_Almquist_shell). See: DashAsBinSh

let is a bash builtin command, so if you want to run your script in bash, run:

bash script

Or make your script executable and use a shebang (http://en.wikipedia.org/wiki/Shebang_(Unix)):


sisco@acme:~$ chmod +x script
sisco@acme:~$ cat script
#!/bin/bash

let x=100
echo $x

sisco@acme:~$ ./script

[shashanksingh]

EDIT: I'm too slow. holiday and shashanksingh beat me to it. :)

In Ubuntu, the default system shell, /bin/sh, is dash (http://en.wikipedia.org/wiki/Debian_Almquist_shell). See: DashAsBinSh

let is a bash builtin command, so if you want to run your script in bash, run:

bash script

Or make your script executable and use a shebang (http://en.wikipedia.org/wiki/Shebang_(Unix)):


sisco@acme:~$ chmod +x script
sisco@acme:~$ cat script
#!/bin/bash

let x=100
echo $x

sisco@acme:~$ ./script


I have a doubt.
When I checked my /etc/passwd
bash was the default shell for both root as well as for myself

but when I executed the above script, it still runs on dash???

[webusr1]

Thanks guys! Adding shebang to line one and making testscr file executable solved my problems. Moving ahead learning Linux on Ubuntu 10.04!!!

Here's my terminal output:

etcmon@etcmon-laptop:~$ chmod 755 testscr
etcmon@etcmon-laptop:~$ ls -l testscr
-rwxr-xr-x 1 etcmon etcmon 19 2011-04-22 12:26 testscr
etcmon@etcmon-laptop:~$ head testscr
#!/bin/bash
let x=100
echo $x

etcmon@etcmon-laptop:~$ ./testscr
100

[rafia2k]

In Ubuntu, the /bin/sh link points to dash. So you will have to specify bash in your script.

#!/bin/bash
let x=100
echo $x

Make the file executable and run it.

$ chmod +x testscr
$ ./testscr

or

$ bash testscr

It is working thanks