TITLE: Bash script to download audio from Youtube
DATE: 2024-06-26
AUTHOR: John L. Godlee
====================================================================
This post is actually about a trick I learned that allows bash
scripts to accept input either as a string or from stdin.
Here is the code. It first checks whether at least one argument is
provided to the script. If an argument is found it creates a
variable containing all the arguments. If no arguments are found,
then it waits for input from stdin, which can either come from a
pipe or can be typed in after the script is called.
#!/usr/bin/env bash
# If argument provided
if [ $# -gt 0 ]; then
input="$*"
else
# Read from stdin
while IFS= read -r line; do
input+="$line"
done
fi
echo $input
I used this trick to write a script to download audio files from
Youtube using yt-dlp. I wanted to be able to integrate the script
with ytfzf, which can search Youtube from the terminal using FZF
and optionally print the URL of the selected video.
[yt-dlp]:
https://github.com/yt-dlp/yt-dlp
[ytfzf]:
https://ytfzf.github.io/
#!/usr/bin/env sh
# Download audio only using yt-dlp
# If argument provided
if [ $# -gt 0 ]; then
input="$*"
else
# Read from stdin
while IFS= read -r line; do
input+="$line"
done
fi
# Download
yt-dlp \
-f bestaudio \
--extract-audio \
--audio-format m4a \
-S +size,+br \
-o "$PWD/%(title)s.%(ext)s" \
--external-downloader aria2c \
--external-downloader-args "-x 5 -s 5 -j 5 -c -k 1M" $input
The script can be called in various ways.
Passing an argument:
yt_audio
https://www.youtube.com/watch?v=Atkp8mklOh0
Using stdin:
echo "
https://www.youtube.com/watch?v=Atkp8mklOh0" | yt_audio
Using stdin with ytfzf:
ytfzf -L Terry Barentsen Hotline Cooper Ray | yt_audio
With multiple URLs as arguments:
yt_audio
https://www.youtube.com/watch?v=WyV894c8oqI
https://www.youtube.com/watch?v=Atkp8mklOh0
With multiple URLs from stdin:
echo "
https://www.youtube.com/watch?v=WyV894c8oqI
https://www.youtube.com/watch?v=Atkp8mklOh0" | yt_audio
