Exec format error for command

When I was trying to run all scripts in a directory using run-parts command, I encountered with an error — «run-parts: failed to exec script.sh: Exec format error». The scripts worked just fine when I directly execute them like «./script.sh» and «sh script.sh». But they didn’t work when I ran them with run-parts command. For those wondering, the run-parts command will run all scripts in a directory. If you got an error like this while running a script, this quick tip will help you to fix «Exec format error» when running scripts with run-parts command in Linux.

Fix «Exec format error» When Running Scripts With run-parts Command

To run all scripts in the Documents folder, I ran:

$ run-parts --regex '^s.*.sh$' Documents/

I got the following error message:

run-parts: failed to exec Documents/script1.sh: Exec format error
run-parts: Documents/script1.sh exited with return code 1
run-parts: failed to exec Documents/script2.sh: Exec format error
run-parts: Documents/script2.sh exited with return code 1
run-parts: failed to exec Documents/script3.sh: Exec format error
run-parts: Documents/script3.sh exited with return code 1
run-parts: failed to exec Documents/script4.sh: Exec format error
run-parts: Documents/script4.sh exited with return code 1

To fix «Exec format error», you need to add a shebang at the start of your scripts so the kernel will know how to run them. For those wondering, a shebang is the character sequence consisting of the characters number sign and exclamation mark (#!) at the beginning of a script. When you add the shebang at the start of a text file, it is interpreted as an executable file.

Most scripts starts with a shebang. Here are some typical shebang examples.

Bourne shell, or a compatible shell:

#!/bin/sh

Bash:

Perl:

Python 2.x:

Python 3.x:

This is what we call a shebang.

Now, let us get back to the topic. Edit your scripts using your favorite editor:

$ nano Documents/ostechnix.sh

Add the following shebang at the beginning of the script:

#!/bin/sh

Now you can be able to run the scripts with run-parts command without any issues using run-parts command.

Update:

As one of our reader Mr.Danesh mentioned in the comment section below, Instead of hard-coding the path of the interpreter, e.g.

#!/usr/bin/python3

We can use:

#!/usr/bin/env python3

This is more portable in case the interpreter is installed in some other (non-default) directory. env is a shell command for Linux and Unix-like operating systems. It is often used by shell scripts to launch the correct interpreter.

You can also use ShellCheck utility to find problems in your shell scripts.

• ShellCheck – A Free Utility To Find Bugs In Your Shell Scripts

Hope this helps.

The oserror: [errno 8] exec format error often can be encountered in different instances on LINUX systems. This article explains its origination and the reasons behind it. Furthermore, it also decodes interesting tricks that can be easily done to solve those reasons. This short guide is the best resource to aid your scripting skills in the right direction.

Why Is Oserror: [Errno 8] Exec Format Error Happening?

Oserror: [errno 8] exec format error originates due to a combination of errors while executing a script in a UNIX server. Some common reasons are the absence of a shebang line, an invalid format of the script, an incorrect path to ffmpeg, and not supported Werkzeug version.

– Absence of a Shebang Line

The location of a shebang line is at the top of a shell script. Its absence can cause the oserror: (errno exec format error subprocess call as attempts are made to directly execute the script. The following is a code example that results in the error by reproducing this issue:

>>> with open (‘a’,’w’) as f: f.write (‘exit 0’) # creation of the script
…
>>> import os
>>> os.chmod (‘a’, 0b111101101) # rwxr-xr-x make it executable
>>> os.execl (‘./a’, ‘./a’) # execute it

The placement of a shebang line is linked with the occurrence of the oserror: (errno exec format error python script. Even though its inclusion followed by the executable of the relevant shell holds no mandatory purpose for the implementation of a script. It means that writing a simple script with the involvement of the execute permission and running it using the “.” operator is possible.

The implementation can be executed by the relevant login shell. The following is a code example that runs successfully:

cat sample
echo “Hello World”
chmod u+x sample
./sample

The output of this implementation is:

Importance of a Shebang Line for the Error

Considering its optional inclusion above, a shebang line is still important in determining the occurrence of the oserror: (errno exec format error mac. The “#!/bin/bash line is included in the shell scripts right at the start of any script. Nowadays, there are different shells available for both UNIX and LINUX systems.

Even though the general syntax may be common among them, different shells have different ways of handling the specific aspects of a script.

This is why the absence of a shebang line causes the oserror errno 8 exec format error robot framework. The lack of specification for a correct shell interpreter corresponds to the failed implementation of a script. In this way, there can be a variation of results with scripts that run in different shells.

– Invalid Format of Script

The display of the oserror: (errno exec format error flask can also be an indication of the possible invalid format of the relevant script. The following snippet can be run to find out the aspects of the format. After this, they can be used to conduct a comparison between the architecture and the output of $ uname –m:

$ file /usr/local/bin/script

– Incorrect Path to Ffmpeg

The oserror: (errno exec format error ffmpeg can occur if the path taken to either ffprobe or ffmpeg is inaccurate. In another case, the files that are being pointed out are not the relevant valid binaries. As a result, the precompiled ffmpeg binaries may not run on the OSX box, although they may run on Synology.

In addition, a ffmpeg executable may already be installed within the Video Station package of Synology Diskstation. The following is a snippet that shows what it may look like:

DiskStation> find / -type d -name ffmpeg
/volume1/@appstore/MediaServer/lib/ffmpeg
/volume1/@appstore/VideoStation/lib/ffmpeg
/volume1/@appstore/AudioStation/lib/ffmpeg

– Werkzeug Version Not Supported

Since version 0.14 of Werkzeug is not supported, this may lead to the occurrence of the oserror: (errno exec format error docker. The involvement of the docker is a new behavior in its version 0.15, where going down to Werkzeug 0.14.1 might work. Therefore, the issue with the relevant file must be corrected.

How Can the Error Be Solved?

Oserror [errno 8] can be fixed by adding a shebang line that acts as a great counter to the error. Parsing the command line is another measure that can be taken to fix the error. Moving on, disabling the debug mode and functioning executables and execution permissions are also some options that can counter the error.

– Adding a Shebang Line

A shebang line can be added with #!/bin/sh prepended at the top of the relevant script if it is a shell script. Here is an example that shows how it can be done with the execution of exit 0 and no occurrence of errors:

>>> with open(‘a’,’w’) as f: f.write(‘#!/bin/shnexit 0’)
>>> os.execl(‘./a’, ‘./a’)

Syntax of a Shebang: A Quick Glance

As a combination of the exclamation mark and pound key, a shebang acts as a character combination that possesses a specific meaning in scripting. It is used as the first member of the first line in every script. Its usage corresponds to the specification of the interpreter that enables the relevant script to run by default.

For example, “#!/bin/bash” can be the first line of any script and signify that the interpreter of the implementation is a bash shell. The first line can also be “#!/bin/zsh” which corresponds to the Z shell as the interpreter. The syntax of a shebang (#!) enables the users to differentiate between itself and comments in shell scripts as both of them have different meanings.

– Parsing the Command Line

The invalid format of the script can be fixed by parsing the command line. Parsing is conducted by the shell on POSIX systems in which the aspects of a valid format are iterated. For example, there are no spaces around the equals “=” sign. This can be seen in the following script:

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

This is the implementation when this script runs in the shell:

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

The following is the output of this implementation in which there are no spaces around ‘=’. Moreover, there is an addition of quotes around <hostname> so that the redirection meta characters ‘<>’ can be escaped:

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

– Functioning Executables and Execution Permissions

The error caused by an incorrect path to ffmpeg can be solved by ensuring that the executables are functioning correctly. Furthermore, they must have execution permissions with certain precompiled ffmpeg binaries taken up as well. These binaries can be swapped in to keep a check on the persistence of the error. As for the snippet above, the autoProcess.ini path can be updated so that it corresponds to the new location:

ffmpeg = /volume1/@appstore/VideoStation/lib/ffmpeg

Disabling the Debug Mode

The file issue can be corrected by disabling the debug mode so that the reloader cannot be used. Keep in mind that neither debug=True nor set FLASK _DEBUG=0 should be debugged. With this, the issue can never occur with the downside of not being able to use the reloader.

In addition, it can be fixed if there is an interpreter line for those files that are marked as executable like #!/usr/bin/env python3. The following is a snippet that shows how to do that:

if __name__ == “__main__”:
connexion_app.run(host=”0.0.0.0″, port=constants.API_PORT, debug=True)

Conclusion

This article put forward a layout of the occurrence of the error in many instances. Let’s look at the main points:

• The error can occur if the shebang line is absent at the top of the script.
• An incorrect path taken to either ffmpeg or ffprobe can also result in the occurrence of the error.
• Although the docker is involved in version 0.15 of Werkzeug, its version 0.14 is not supported; therefore, the error can originate.
• A shebang line is a combination of the exclamation mark and pound key and can be added to the top of the script.
• The executables should function properly and contain their execution permissions accompanied by precompiled ffmpeg binaries.

This article can help you whenever you are on the lookout for any information about this error.

Receiving a Docker exec format error when you run the Docker? We can help you fix it. 

The Docker exec format error is a common error, and we fix the error by adding shebang in the entrypoint of the script.

At Bobcares, we get requests to fix docker exec format error, as a part of our Server Management Services.

Today, let’s have a look at how our Support Engineers fix this error.

Explore more about Docker

The docker container which allows OS level virtualization and is also known as containerization. The main benefits of the docker is to package applications in container and the container is portable to Linux or Windows operating system.

Docker container is a software stores up code and all its dependencies. So that the application runs fast and consistently good in quality and performance.

But, many times Docker container will end up with exec format error. Let’s see how our Support Engineers fix it.

Why does Docker show exec format error?

We see the below docker error when we launch the docker container.

Whenever our customers have such an error, our Support Engineers check the entrypoint in the Docker file.

A Docker file is the text document that use all the commands that a user could call on the command line to assemble an image.Also in Docker file we can write the instructions to build a Docker image.

The sign of this error is that the docker entrypoint script was missing a shebang. So to fix the error we add the shebang in the script.

How we fix the exec format error?

We fix this docker error by adding the shebang on the entrypoint of the script. The shebang is a special character sequence in a script file that specifies which program should be called to run the script.

The shebang is always on the first line of the script, and is composed of #! Characters. So the Shebang (#!/bin/bash) should be put on the first line of the script because the first bytes were checked by kernel. So we add the shebang in the script.

#!/bin/bash

The other method to fix the docker error is that we have to run the below command.

$ docker run -entrypoint="/bin/bash" -i test

This fixes the docker error.

[Need help in fixing Docker format error? – We’ll help you.]

Conclusion

In short, The Docker error occurs due to missing of the shebang in the script. The default entrypoint does not know how to run the script. Today, we saw how our Support Engineers fix this error for our customers by adding the shebang at the entrypoint of the script.

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