bash: Permission denied? Why your script will not run

bash: ./script.sh: Permission denied almost never means you lack rights to the file’s contents: it means the file is not marked executable, or it lives on a filesystem mounted so that nothing on it can execute. Two very different fixes, so identify which one you have.

The usual cause: no execute bit

A freshly downloaded or newly written script has no x permission. Add it:

chmod +x script.sh
./script.sh

Check what you have with ls -l. You want to see an x in the owner column:

ls -l script.sh
# -rw-r--r--  → not executable
# -rwxr-xr-x  → executable

The chmod calculator translates between the letters and the numbers: rwxr-xr-x is 755, rw-r--r-- is 644.

The workaround that always tells the truth

Call the interpreter directly. If this works but ./script.sh does not, the problem was definitely the execute bit, not the code:

bash script.sh
sh script.sh
python3 script.py

When chmod does not help: noexec mounts

/tmp, /dev/shm and some home partitions are frequently mounted noexec for security, so nothing on them may run regardless of permissions. Check with:

mount | grep -E '/tmp|/home'
# look for the word "noexec" in the options

• Move the script to a normal path such as your home directory and run it there.
• Or invoke the interpreter explicitly (bash /tmp/script.sh), which sidesteps the exec check.

A related trap: the shebang

If the script is executable but you get bad interpreter or a cryptic error, the first line may point at a missing interpreter or carry Windows line endings. Check and strip carriage returns:

head -1 script.sh          # should be e.g. #!/usr/bin/env bash
sed -i 's/\r$//' script.sh  # remove trailing \r from Windows editors

“Permission denied” on cd or a file you own

Entering a directory needs its execute bit; reading a file needs read on the file and execute on every directory above it. If cd is refused:

chmod +x /path/to/dir      # execute = "may traverse"
ls -ld /path /path/to /path/to/dir

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