What is the difference between a script starting with:

#!/bin/ksh

and

#!/bin/sh


thanks

ksh is korn shell.
Sh is bourne shell.

Script starting with #!/bin/ksh is executed by Korn shell
Script starting with #!/bin/sh is executed by Bourne shell

ok, and what is korn and bourne? it sounds like the very best friends one should have at unix (sorry I am a noob at unix)

The problem is that I have that simple script here:

and I am not sure if I have to put ksh or sh in the first line.

Which first line do you mean? The delaration at the top means this script will run as a ksh script. The script definition effects the syntax in the script.

The file is sysdba.sh and the first line of the file is #!/bin/ksh

the #!/bin/ksh at the top of the file define what the following commands in the script use as an interpreter, in this case /bin/ksh (the korn shell)

you can put practically any interpretive shell command there, i.e.

#!/usr/bin/awk for awk
#!/usr/bin/perl for perl

and so on. putting a ':' there will mean use the default shell

the difference between sh and ksh (bourne and korn) is mostly functionality. i.e. ksh has variable substitutions, dimensioned arrays, etc

Also good to know is anything written for bourne shell can run in korn shell. As TinWalrus stated, korn shell has more functionality.

Now the #! ( pronounced Shebang ) line of the script just tells the script what shell to use when executing. So say you use bourne shell and have a script that uses functionality of korn shell you could run the script in your bourne shell provided you have included the line #!/usr/bin/ksh
If you didn't include this, your script might return an error.

( Thanks for the correction reborg. )