Shell Programming and Scripting

Hi,

As per my understanding, we can use two shebang statements in a single shell script. Please see below snippet-

#!/bin/bash
.......## some code A
#!/bin/csh
.......## some code B
exit 0;


Here, code A will be executed using bash shell and code B will be executed with c shell.

Please let me know, in case, if I'm wrong.

Also, please tell me how to know the current running shell in shell script.



Regards,
Tarun0

no you cannot use it.

The shebang works only when
1. it is on the first line
2. it starts in column one

If you need to run some code in another shell -

Code:

#!/bin/bash
....
...
/bin/ksh -c ' your command goes here'  # can't type - removed shebang

This executes one line using ksh. Otherwise you have to invoke the other shell in a separate script.

Code:

#!/bin/bash
/path/to/script.csh
/path/to/anotherscript.ksh

I added .csh and .ksh extensions to show what shell they use, the .ksh extension, for example, has no effect on actual shell choice in the script.

Without the shebang then, no?

Code:

/bin/ksh -c ' your command goes here'

scrutinizer - thanks, I fixed it. My bad.

Thanks guys !

Still there is one doubt!

what happens when we source a script having shebang statement of C shell(for instance) into the script having shebang statement of K shell?

In this case, does the sourced script(with C shell shebang) execute in C shell(child process) and return the output in running script with K shell(parent shell) shebang.

See below snippet-

running script is -
#!/bin/ksh
...some code...
source <sourced script name>
exit 0;

where the sourced script is -
#!/bin/csh
...some code;
exit 0;

You cannot source the csh script inside the ksh script, you need to execute it so that it runs in a separate (c-)shell