How to fix exec user process caused: permission denied in Docker

The most common fix is to explicitly set execute permissions in your Dockerfile after copying the script:

COPY entrypoint.sh /entrypoint.sh
RUN chmod +x /entrypoint.sh
ENTRYPOINT ["/entrypoint.sh"]

If you're copying multiple scripts:

COPY scripts/ /scripts/
RUN chmod +x /scripts/*.sh

Important: Always use the exec form (JSON array) for ENTRYPOINT, not the shell form.

If you edited the script on Windows, convert line endings in your Dockerfile:

COPY entrypoint.sh /entrypoint.sh
RUN sed -i 's/\r$//' /entrypoint.sh
RUN chmod +x /entrypoint.sh
ENTRYPOINT ["/entrypoint.sh"]

Or install and use dos2unix:

RUN apt-get update && apt-get install -y dos2unix
COPY entrypoint.sh /entrypoint.sh
RUN dos2unix /entrypoint.sh && chmod +x /entrypoint.sh

Better long-term fix: Configure Git to preserve LF endings for shell scripts by adding a .gitattributes file:

*.sh text eol=lf

Ensure your script starts with a valid shebang on the very first line:

#!/bin/bash
# or for Alpine/minimal images:
#!/bin/sh
# or for maximum portability:
#!/usr/bin/env sh

Common mistakes:
- Shebang not on line 1 (blank line or BOM before it)
- Wrong interpreter path (/bin/bash doesn't exist in Alpine, use /bin/sh)
- Invisible characters before the #

Check for hidden characters:

head -1 entrypoint.sh | cat -A

You should see exactly #!/bin/bash$ (or similar). Any ^M indicates CRLF line endings.

Docker's COPY instruction preserves file permissions from your build context. Fix permissions on your host machine:

chmod +x entrypoint.sh
docker build -t myimage .

This is simpler than adding RUN chmod in your Dockerfile, but requires remembering to set permissions before each build (or committing the executable bit to Git).

Verify the file is executable:

ls -la entrypoint.sh
# Should show: -rwxr-xr-x (the x's indicate execute permission)

If you can't modify the Dockerfile or need a quick workaround, explicitly invoke the shell:

ENTRYPOINT ["sh", "/entrypoint.sh"]
# or
ENTRYPOINT ["/bin/sh", "-c", "/entrypoint.sh"]

Or override at runtime:

docker run myimage sh /entrypoint.sh

This bypasses the execute permission check since sh reads and interprets the file rather than executing it directly. However, this is a workaround, not a proper fix.

If you're on a system with SELinux enabled and the above fixes don't work:

Check if SELinux is blocking:

sudo ausearch -m avc -ts recent | grep docker

Temporary workaround (not for production):

sudo setenforce 0
docker run myimage

Proper fix - relabel Docker storage:

sudo semanage fcontext -a -t container_file_t "/var/lib/docker(/.*)?"
sudo restorecon -R /var/lib/docker

Or use the :Z flag when mounting volumes:

docker run -v /host/path:/container/path:Z myimage