Hello to all,

this is my first post.

i am in need to use "exec -a java mono rename.exe" in shell script.
but when i do the same in script it gives error that "-a: not found"

plz help me to achieve this with shell script or simple C program

Are you using Bash? The -a option to exec is not in the POSIX spec; it is only a Bash feature. If you're using some other shell, it won't work.

yes i am using the Bash. but its noting working

Please show the script so we may have a better idea of the issue?

Just to confirm, your current shell is also bash? (ie output of echo $SHELL)

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here is my script code

#!bin/sh
exec -a java mono rename.exe


also i tried c code for this as....

#include<stdio.h>
void main()
{
system("exec -a java mono rename.exe ");
}

compile this with gcc and run this but same error -a not found

#!bin/sh

I don't know much about shell scripting but this should be

#!/bin/sh

...but maybe just a typo in the post?

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j-ray is right about the missing /, but #!/bin/sh is still incorrect. -a is not an option to exec when using a POSIX shell (sh.) You want to be using bash as the interpreter, if you're going to keep the -a.

Change it to #!/bin/bash

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jhwilliams is of course correct. I do always find it interesting that what someone says and then when they show the example are often different things.
Apart from the typo these two statements are not the same

Please use [code][/code] tags around your code and data, to preserve formatting and to improve readability.


To be fair, a lot of people don't really understand what the shebang does. They run the script from their bash consoles, but don't realize that that first line in the script is what tells the system which interpreter to use for it. The shell you launch it in doesn't matter when you execute a script directly.

And for the record, the default "/bin/sh" interpreter may actually be bash, depending on how your system is configured. But sh is always treated as a posix-compliant script, and even bash will ignore or error out on most non-posix structures inside such a script.

Of course, you can alternately run a script by directly specifing the interpreter you want as the program name, and pass the script itself to it as an argument. Run this:

...and it will be interpreted as a bash script, no matter what the shebang says (since the line starts with #, it's treated as a simple comment).


BTW, The c code likely doesn't work because exec is not a stand-alone program, but a shell built-in. The system function isn't told what interpreter to use for that command.

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Especially as there is the default /bin/bash in Linux, hence it even runs with a typo in the first line most likely in the way you expect it.

To the original problem: whether I use #!/bin/sh or #!/bin/bash doesn’t matter, it always accepts -a. I assume the original poster is using Solaris, where the default may be csh. And as a result of the typo the default csh on Solaris is used for the script and throws the error as in csh the option -a isn’t allowed to exec.

I disagree; probably that sh is a symbolic link to the more common dash or busybox; csh has mostly been tossed in the trash by now. To that point: are you kidding me, Solaris defaults to csh?

/bin/sh on linux is generally a link to /bin/bash

and it generally isn't compatible with POSIX /bin/sh
even though it claims to be.

It generally doesn't fail where it would on unix /bin/sh

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How are the following different?

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The first one replaces the shell process with the java process, and the second one causes the shell to wait until the java process finishes, and then continue.