shebang not working to run bash scripts in linux

Question

I can't seem to get bash scripts to turn into executable files via shebang. My code looks like

#!/bin/bash
echo "hello"

where this is in a file called test.sh. I'm trying to get it to run with the command

./test.sh

in the command line but i just receive the error of permission denied. When i change it to

sudo ./test.sh

I just get back that command not found. I can turn the file into an executable via the command the command line:

chmod +x test.sh

and the code correctly outputs

hello

I've tried the commands

which bash

which returned the directory /bin/bash and I've also exported this path in my .bashrc to no avail. Any ideas would be greatly appreciated thanks! I'm running Linux mint just for clarity.

Are you entering "./test.sh" on the command line, or something else? What message do you get? — L. Scott Johnson, Jun 05 '18 at 14:12
oh sorry i completely forgot to write that. I'm entering ./test.sh into the command line and it says permission denied. When i type sudo ./test.sh it just says command not found. — Anthony Kalaitzis, Jun 05 '18 at 14:15
Check that chmod +x is actually working: ls -l the file and verify that it has execute permission set. — L. Scott Johnson, Jun 05 '18 at 14:16
Does it work if you remove the "#!/bin/bash" from the script file? — L. Scott Johnson, Jun 05 '18 at 14:17
stat test.sh outputs [ File: 'test.sh' Size: 33 Blocks: 8 IO Block: 4096 regular file Device: 802h/2050d Inode: 2239860 Links: 1 Access: (0664/-rw-rw-r--) Uid: ( 1000/ anthony) Gid: ( 1000/ anthony) Access: 2018-06-05 23:44:51.276196037 +0930 Modify: 2018-06-05 23:44:51.276196037 +0930 Change: 2018-06-05 23:44:51.276196037 +0930 Birth: - ] — Anthony Kalaitzis, Jun 05 '18 at 14:19
chmod +x test.sh definitely works. Changes it into an executable that runs with ./test.sh like i want. — Anthony Kalaitzis, Jun 05 '18 at 14:20
i want it to run after just ./test.sh without using the command chmod +x. Isn't that hows shebangs work? — Anthony Kalaitzis, Jun 05 '18 at 14:22
The shebang just tells the executor what shell or other program (perl, etc.) to use to read the commands. — L. Scott Johnson, Jun 05 '18 at 14:23
You did it. #!/bin/bash says to use bash. chmod +x says to let you execute the file as a command. — L. Scott Johnson, Jun 05 '18 at 14:24

score 0 · Answer 1 · answered Jun 05 '18 at 14:25

0

chmod +x test.sh

Setting the executable bit is exactly what's needed. A script needs both a shebang line and executable permission to be run. Otherwise you have to invoke a shell explicitly with, say, bash test.sh. The executable bit lets you write ./test.sh.

answered Jun 05 '18 at 14:25

John Kugelman

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the script works without the shebang though if i do the chmod + test.sh. So whats the purpose of the shebang then? – Anthony Kalaitzis Jun 05 '18 at 14:28
It's redundant if the shebang is #!/bin/bash and your interpreter is bash. But if the shebang is "#!/usr/bin/env python" and the script is written in python, or maybe if the script gets run in a shell other than bash (rare I suppose) it makes a lot of difference. – poleguy Nov 03 '21 at 14:05

shebang not working to run bash scripts in linux

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