Bash error: "Permission denied"

Error String

bash: ./script.sh: Permission denied

Tldr

"Permission denied" when executing a file almost always means the execute bit is not set. Run "chmod +x script.sh" and try again. If it still fails, check the shebang line and whether the filesystem is mounted noexec.

Cause

To run a file as a program, the user invoking it needs the execute permission on that file. New files created by editors, downloaded with curl, or extracted from tarballs often lack +x. A less common cause is mounting /tmp or a removable disk with the noexec option, which disables execution regardless of the file mode.

Repro

$ ./deploy.sh
bash: ./deploy.sh: Permission denied

$ ls -l deploy.sh
-rw-r--r--  1 you  staff  142 Jun 16 10:00 deploy.sh   # no x bit

Fix

# Add execute for the owner (and optionally group/others)
chmod +x deploy.sh
./deploy.sh

# Or run it explicitly with bash, which only needs read permission:
bash deploy.sh

# If chmod doesn't help, the filesystem may be noexec:
mount | grep "$(df . | awk 'NR==2 {print $1}')"
# Look for "noexec" in the options. Move the script to a normal mount.

Explanation

Executing a script via "bash script.sh" bypasses the +x check because bash itself reads the file. That is a useful workaround but it skips the shebang too, so the script runs under whichever bash is on your PATH. Setting +x and running it directly honors the #! line, which is usually what you want.

Faq