A user-friendly bash script for playing content on a TV through Raspberry Pi

rpi-tv-select.bash

#!/bin/bash

# This script collects files in a media folder and presents them in a dialog,
# where you can select one with arrow keys and enter. It is then played with
# omxplayer.
# The script allows navigating into subdirectories, and back up as well. Spaces
# in file names should also work properly.

# Assumptions:
# - `whiplash` is installed. `dialog` is an alternative, but it didn't work well
#   for me.


# Directory containing TV. You will need read access.
# Won't allow navigating up beyond this point.
mainTvDir="/mnt/TV/"

# Current directory we're listing files in
tvDir=${mainTvDir}

# Directory we're in at launch, so we can return to it at exit
initialPwd=$(pwd)

# Dialog dimensions based on terminal size
dHeight=$(($(tput lines)-4))
dWidth=$(($(tput cols)-4))
choiceHeight=$((dHeight-11))

# Where to direct terminal output
terminal=$(tty)

# Array of entries in current directory
fileList=("")

# Start in the tv directory
cd $tvDir
# At bottom of file, after all functions are implemented, we invoke main.


# Gets called at the beginning, and every time we need to refresh / return
# or navigate to a different folder
main() {
  # Load the list of files into fileList
  getFiles

  # Show navigation dialog and await user choice
  local choice=$(getChoice)

  if [[ -z $choice ]]; then
    # If no choice was given, this indicates "exit" (cancel) was picked.
    # Ask whether to indeed exit
    askExit
  elif [[ $choice = "reload" ]]; then
    # If refresh was picked, just run main again which will get a new list of
    # files. Do this if you've added files to the directory after starting the
    # script.
    main
  elif [[ $choice = ".." ]]; then
    # Navigate up a directory, then reload file list
    cd ..
    tvDir="$(pwd)/"
    main
  else
    # Any other option is either a directory or a file to try and play.
    # Let navigate deal with it by index in fileList.
    local index=$((choice-1))
    navigate $index
  fi
}

# Collects files and stores them into the fileList array
getFiles() {
  # Clear previous array of files
  unset fileList
  cd $tvDir

  # Populate file list anew with all files found.
  # Note: this previous used `ls`, but that's a bad idea in bash scripts,
  # due to issues with spaces and quotes and such. ls isn't meant for script
  # parsing.
  for f in *; do
    fileList+=("$f")
  done
}

# Present a dialog with directory entries and a couple of options to the user
getChoice() {
  # tag counter for whiptail dialog - each entry gets a tag. Our file/directory
  # entries get a numeric tag.
  local cnt=1

  # Array index for menu options. Every menu entry takes two array entries:
  # One tag, one item.
  local i=2

  # Array to contain menu options
  local menuOpts=(reload "[Refresh]")

  if [[ "$tvDir" != "$mainTvDir" ]]; then
    # If we're not in the top level TV directory, add an entry to go to the
    # parent directory
    menuOpts+=(.. "../")

    # Increase array index by two, for the entries we've just added
    ((i+=2))
  fi

  # Add menu entries for each entry in fileList
  for file in "${fileList[@]}"; do
    # Assign numeric tag
    menuOpts[i]=$cnt

    if [[ -d $file ]]; then
      # If the entry is a directory, add the "/" suffix as a visual indicator
      menuOpts[i+1]="$file/"
    else
      # Otherwise just use the filename as-is
      menuOpts[i+1]="$file"
    fi

    # Increment menuOpts array index by the two entries just added
    ((i+=2))

    # Increment tag counter by one
    ((cnt++))
  done

  # Render menu and output choice to terminal
           # Line by line comments:
           # Print the current directory in the back
           # Set title on the dialog
           # Don't display tags as they're useless here
           # Chunky buttons
           # Use "Exit" as the text for the cancel button
           # Start menu options + text above menu
           # Pass dialog dimensions (height, width, choice area height)
           # Pass all the menu options
           # Redirect all output to the tty
  whiptail --backtitle "$tvDir" \
           --title "Select file" \
           --notags \
           --fullbuttons \
           --cancel-button "Exit" \
           --menu "Select a file to watch" \
           $dHeight $dWidth $choiceHeight \
           "${menuOpts[@]}" \
           2>&1 > $terminal
}

# Navigate to an item by index (in $1), corresponding to an item in $fileList
# If this is a directory, navigates to that directory and renders the menu again
# If it's a file, attempt to play it with omxplayer, then render menu again
navigate() {
  local fullFilePath="${tvDir}${fileList[$1]}"

  if [[ -d $fullFilePath ]]; then
    # If it's a directory, set that as our working directory and go back to menu
    tvDir=$fullFilePath
    main
  else
    echo "Trying to play ${fileList[$1]} with omxplayer..."
    mediaFile=("${fileList[$1]}")

    omxplayer "$mediaFile"
    main
  fi
}

# Prompt user whether to exit, with optionally a custom message.
# If Yes is picked, the script returns to the original directory, and exits.
# Otherwise, it returns to the main menu.
askExit() {
  msg=$1

  if [[ -z $msg ]]; then
    msg="Are you sure you wish to exit?"
  fi

  if (whiptail --yesno "$msg" \
                       7 34 \
                       2>&1 > $terminal); then
    echo "Bye."
    cd $initialPwd
  else
    main
  fi
}

# Launch main menu
main