Convert line endings with dos2unix

Windows uses CRLF (\r\n) line endings; Linux uses LF (\n). When a .sh script makes the trip from a Windows editor to a Pi-class device, bash sees the carriage return as part of the shebang — #!/bin/bash\r — and refuses to run the script. The error you’ll see is misleading:

-bash: ./your_script.sh: /bin/bash^M: bad interpreter: No such file or directory

It looks like the interpreter is missing. It isn’t — the line endings are wrong. dos2unix strips the \r and the script runs.

This bites you almost every time you copy a script from a Windows machine to the FR201 over a USB stick or via SCP.

Install dos2unix

Install on Raspberry Pi OS

sudo apt-get install dos2unix -y

Convert a single script

Convert and run a script

dos2unix your_script.sh
sudo chmod +x your_script.sh
./your_script.sh

Convert many files at once

If you’ve just copied a directory of scripts onto the device, use find to convert in bulk.

Convert every file in the current directory (non-recursive):

Convert files in this directory

find . -maxdepth 1 -type f -exec dos2unix {} \;

Convert only shell scripts, recursively:

Convert all .sh files recursively

find . -type f -name "*.sh" -exec dos2unix {} \;

Convert every file under the current tree:

Convert everything (use with care)

find . -type f -exec dos2unix {} \;

Then make the shell scripts executable in one pass:

Mark scripts executable

find . -type f -name "*.sh" -exec chmod +x {} \;

Automate the USB-drive copy

If you’re constantly hand-carrying scripts on a USB stick, automate the convert-and-copy step. The script below mounts a USB drive, converts every file from CRLF to LF, copies the tree to a destination directory, and marks the shell scripts executable.

See the Mount a USB drive guide for how to set up the mount point.

1. Create the helper script in your home directory:

   Create the helper script

   sudo nano /home/pi/convert-files-on-copy.sh

2. Paste in the contents below. Adjust USB_MOUNT and DEST to match your setup:

   /home/pi/convert-files-on-copy.sh

   #!/bin/bash
   # Converts CRLF to LF on every file on a mounted USB drive,
   # copies the tree to DEST, and marks shell scripts executable.
   
   USB_MOUNT="/media/usbdrive"
   DEST="/home/pi/scripts"
   
   if ! mountpoint -q "$USB_MOUNT"; then
       echo "USB drive not mounted at $USB_MOUNT. Mount it first."
       exit 1
   fi
   
   echo "Converting files from Windows format..."
   find "$USB_MOUNT" -type f -exec dos2unix {} \;
   
   echo "Copying files to $DEST..."
   mkdir -p "$DEST"
   cp -r "$USB_MOUNT"/* "$DEST"/
   
   echo "Marking shell scripts executable..."
   find "$DEST" -type f -name "*.sh" -exec chmod +x {} \;
   
   echo "Done."

3. Make it executable:

   Mark the helper executable

   sudo chmod +x /home/pi/convert-files-on-copy.sh

4. Run it whenever you’ve plugged in a fresh USB stick:

   Run the helper

   /home/pi/convert-files-on-copy.sh

Avoid the problem entirely

If you control the source machine, configure your editor (VS Code, Notepad++, Sublime, etc.) to save files with LF line endings. In VS Code, set "files.eol": "\n" in settings.json. A .gitattributes file with *.sh text eol=lf enforces it for anything checked into Git.