How to start a bash script on Oracle Linux

Question

What is the right way to start a bash script on Oracle Linux?

on a normal Linux server I use ./script.sh

But here is what I got when I do the same on Oracle Linux

[user@server ~]$ ./script.sh
bash: ./script.sh: Permission denied

The permissions are correct

[user@server ~]$ ll script.sh
-rwxr-x--x 1 user oraexpl 317 Jul  4 15:42 script.sh

It works ok if I omit the "/" character

[user@server ~]$ . script.sh
It works

It works ok if I execute it with bash

[user@server ~]$ bash script.sh
It works

In my script, I do have the Shebang /bin/bash

Is this behavior normal?

Thanks for your feedback

You write that you execute ./script.sh, but your shell complains about ./script_shell.sh. Please clarify if this is a typo, or if script.sh internally calls script_shell.sh. — AdminBee, Jul 04 '22 at 14:24
Related: What is the difference between sourcing and executing a file in bash — AdminBee, Jul 04 '22 at 14:25
What is the first line in the script? Is it invoking a valid interpreter? And is it possible that the file system is mounted noexec? — doneal24, Jul 04 '22 at 14:54
Bingo, you got it:
/dev/mapper/vg_root-lv_home on /home type ext4 (rw,nosuid,nodev,noexec,relatime) — Angel115, Jul 04 '22 at 17:04
The CIS benchmark calls for noexec on removable media (reasonable), on /dev/shm (also reasonable), and on /tmp (causes lots of problems, with podman, a few flexlm daemons, a few java apps, etc.). Doesn't call for the flag on /home so I think you have an over-zealous admin or security group. — doneal24, Jul 04 '22 at 18:56
What is the output of findmnt --target .? (run in same dir as script) — ctrl-alt-delor, Jul 04 '22 at 18:58

score 2 · Accepted Answer · answered Jul 04 '22 at 18:59

2

Following up as an answer so this can be accepted and searched. Mounting /home with the noexec option will cause this behavior. The mount option is not prescribed by the CIS benchmark so you may have reason to appeal to the system administrator or the security group. If you have sudo privileges, try removing noexec from the options in /etc/fstab. If something like puppet or chef overrides this, you can use

sudo mount -o remount,exec /home; ./script.sh

as a temporary fix for the problem.

answered Jul 04 '22 at 18:59

doneal24

5,059

That would fix the problem, but also allow users to execute their own binary files. Which my customer don't want. But thanks for your help. now I have the explanation for why I have this behavior. – Angel115 Jul 12 '22 at 10:26
1

@Angel115 Just an FYI. Similar to using bash ./script you can use /lib64/ld-linux-x86-64.so.2 ./exe to run a binary executable that you normally would be able to execute. Mounting the FS noexec will slow people done but doesn't eliminate the problem. – doneal24 Jul 12 '22 at 12:21

How to start a bash script on Oracle Linux

But here is what I got when I do the same on Oracle Linux

The permissions are correct

It works ok if I omit the "/" character

It works ok if I execute it with bash

1 Answers1