Mastering Shell scripting
Table of Contents
- 1. Iterate files in a folder
- 2. Rename files in a directory
- 3. DONE Find and copy files from a directory based on creation date
- 4. Read lines from a text file
- 5. Copy mpd playlist songs to a directory
- 6. Similarly you can iterate over file path returned by another command.
- 7. DONE Get file name or file extension
- 8. Search for an image pattern in files in a directory
- 9. Common errors
1 Iterate files in a folder
for f in *.jpg; do echo ${f}; done;
2 Rename files in a directory
Now let us say you want to remove a prefix like small_ from all your file then you can do something like this.
for f in *.mp4; do mv ${f} ${f/small_}; done;
3 DONE Find and copy files from a directory based on creation date
find /srouce/directory/ -type f -newermt 2022-11-12 -exec cp {} /target/directory/ \;
4 Read lines from a text file
This is one of the most useful thing. You may need to read lines from a file and then do something with those line. It could be file paths or anything else.
while read LINE; do echo $LINE; done < list-video.txt;
5 Copy mpd playlist songs to a directory
I love listening to music using mpd which works great but sometimes I prefer syncing and want to copy my favourite songs from my mpd playlists to a specific directory - it could be a mounted mobile directory or ~/tmp or a mounted usb drive.
while read LINE; do cp ~/myfiles/music/"$LINE" ~/tmp/; done < ~/myfiles/music/playlists/feel-good.m3u
Wow shell is so cool ;)
6 Similarly you can iterate over file path returned by another command.
mpc search any nelly | while read -r LINE; do echo music/"$LINE"; done;
Super cool isn't it? Here I was trying to search a song.
7 DONE Get file name or file extension
If you are iterating files in a directory and filename is the variable then you can get the file name or file extension easily.
extension="${filename##*.}" filename="${filename%.*}"
Reference: stackoverflow
8 Search for an image pattern in files in a directory
grep -inH ".png" *.org | cut -d ":" -f 4
-i: ignore case -n: print line number -H: print file name
9 Common errors
- Bash script and /bin/bashM: bad interpreter: No such file or directory
sed -i -e 's/\r$//' scriptname.sh