Handle the Exception ‘Oserror: [errno 8] exec format error’

Python doesn’t need an introduction as it is an integral part of programming that every programmer as well as a beginner is aware of. It has given the liberty to programmers all over the world to develop any application they want according to their set of rules. As it is the most used language, it is obvious to experience errors. Beginners often get worried when they see an error message pop up. You may encounter the error ‘Oserror: [errno 8] exec format error’ that makes you wonder what you have done to get the error warning.

You should not be worried as there is no such error that can’t be fixed. As you came here to get the error resolved, we help you with the solutions that you can simply implement. But before reach to the solution sections, let’s check out how the error occurs

How do you get the error?

When you are using subprocess.Popen for the arguments being parsed. You must be having a tough time executing the code on the Unix server. Have a look at the code

import subprocess
 Out = subprocess.Popen(['/usr/local/bin/script', 'hostname = ', 'actual server name', '-p', 'LONGLIST'],shell=True,stdout=subprocess.PIPE,stderr=subprocess.PIPE)

You end up with the error warning as soon as you import. This is what you get in return

OSError: [Errno 8] Exec format error

Now that you have seen how the error occurs, check out the solution to fix the error

Solutions to Fix ‘Oserror: [errno 8] exec format error’

The error happens because of many errors when you are running a Python script on a Unix server.  The prominent cause of the error is the shebang line’s absence. We have solutions to handle the exception in a simpler way. Have a look at the solutions to fix it

Solution 1 – Add Shebang line

The error pops up when there is no shebang line at the top of the shell script. You may not get any error when running the command in the shell. But the subprocess.check output() can’t just execute or run the shell by default.

Use the following ways to handle the exception

• At the start of the faulty file or the command, add /bin/bash
• In the first line, you need to add the shebang #!/bin/sh

Have a look at the code

#python -c "import pexpect; p=pexpect.spawn('/bin/bash /usr/local/ssl/bin/openssl_1.1.0f version'); p.interact()"
OpenSSL 1.1.0f 25 May 2017

Solution 2 – Add Shebang line

This is another way to add the shebang line at the top of the shell script. If you run the script without the shebang line, you get the error message. Take a look at the example

>>> with open('a','w') as f: f.write('exit 0') # create the script
... 
>>> import os
>>> os.chmod('a', 0b111101101) # rwxr-xr-x make it executable 
>>> os.execl('./a', './a') # execute it 
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
 File "/usr/lib/python2.7/os.py", line 312, in execl
 execv(file, args)
OSError: [Errno 8] Exec format error

To fix it, add the shebang line. On the top of your shell script add #!/bin/sh. The code looks like this

>>> with open('a','w') as f: f.write('#!/bin/sh\nexit 0')
... 
>>> os.execl('./a', './a')

You will not see any error when executing exit 0

On the POSIX system, the command line is parsed by shell. No space around ‘=’ can be seen by the script of yours. In this case, the script is like this

#!/usr/bin/env python
import sys
print(sys.argv)

It runs in the shell like this:

$ /usr/local/bin/script hostname = '<hostname>' -p LONGLIST

And it produces the following code

['/usr/local/bin/script', 'hostname', '=', '<hostname>', '-p', 'LONGLIST']

In order to match the shell command in Python, you should run the following

from subprocess import check_call

cmd = ['/usr/local/bin/script', 'hostname', '=', '<hostname>', '-p', 'LONGLIST']
check_call(cmd)

Make the script in the correct order to avoid the error warning. Follow the below code

$ file /usr/local/bin/script

You can also compare the architecture using the below command

$ uname -m

Conclusion

In this post, we have discussed two solutions to a similar problem to fix the error ‘Oserror: [errno 8] exec format error’. To add the shebang line, we highlighted two possible ways, you can choose that fit the best for you. I wish you luck!

Reference Source: https://www.solved.tips/oserror-errno-8-exec-format-error/

https://www.baeldung.com/linux/shebang