This is a list of useful bash scripts I made, many of which I use on a daily basis.
I have more than these, but they are unique to my situation (think appending a line to a hardcoded file name) and so aren't included.
For the case of an example file named lsdir.sh, you can run them like this, after first making the file executable ("chmod +x lsdir.sh"):
./lsdir.sh
I use Ubuntu and so I often copy these files to ./local/bin and remove the extension, so I can run them from the command line like this:
lsdir
I'm also including many of the bash aliases I use here since they're similar in spirit to many of these scripts, which could often be rewritten as one-line aliases in a .bashrc file.
Disclaimer: many of these scripts were created with the assistance of ChatGPT, which excels at this type of narrowly defined task.
Here is a guide to what these files do.
This script prints out the the contents of the last modified file in the current directory.
Run it like this:
./clast.sh
This script counts the number of files in the current directory and prints the sum out.
Run it like this:
./countfiles.sh
This is for copying the current file over from {name}.{file extension} to {name}_1.{file extension}.
If {name}_1.{file_extension} exists, it will be overwritten.
Run it like this:
./cpone.sh test.py
This script will create a copy of test.py named test_1.py.
This script is for copying the current file over from {name}.{file extension} to {name}_{next available version number}.{file extension}.
If {name}_1.{file_extension} exists, it won't be overwritten.
This means the script won't copy over the current filename into a filename with a version number that currently exists in the same directory. It will keep iterating on the version number until it finds a version number that isn't being used for a filename, and then copy the file over to that filename.
Run it like this:
./cpversion.sh test.py
This script will create a copy of test.py named test_1.py if test_1.py does not exist.
If the directory already has a test.py, test_1.py, test_2.py, and test_3.py, it would create a copy of test.py named test_4.py.
This script uses imagemagick, a software suite for working with images, to create an image of white text on a black background.
To use this script you must have imagemagick installed.
Run it like this:
./create_image_white_text_on_black_background.sh "Live your life."
This script tells you all the files that were last modified on the date you provide.
If you want to know when you last worked on a file, if you give it the day in the format month-day-year, this script will tell you.
Run it like this:
./datecheck.sh 10-19-23
It will tell all you all the files that were last modified on 10-19-23.
This script finds the number of days that have passed between the two days that you give it as arguments.
Run it like this, to find the number of days that have passed between 9/25/23 and 11/10/23:
./daydifference.sh 092523 111023
For this input the output would be '46 days'.
This script is for when you've downloaded a file to ~/Downloads and it has a name like 393248092349809.jpg.
Run it like this, from within your ~/Downloads directory:
./downloaded_file_rename.sh "lake_geneva"
It will rename 393248092349809.jpg to lake_geneva.jpg.
This script returns the size of the filename argument.
Run it like this, to find the size of a file named file.txt:
./filesize.sh file.txt
This script shows all directories in the current directory.
Run it like this:
./lsdir.sh
This script gives the full list of all directories and subdirectories in the current directory. It's a lot more verbose than the version above.
Run it like this:
./lsdirfull.sh
This script takes a file as input and prints out each of its lines surrounded by p tags.
It's meant for plain text files which you intend to upload as simple html pages.
For example, a file with the name file.txt this line:
Today is a nice day.
Would be modified to this:
<p>Today is a nice day.</p>
Run it like this, for an example file.txt file:
./surround_with_p_tags.sh file.txt
This script is for when you have a file like text.txt and you know you want to replace all of one character with another character: for example, replace every occurrence of the "?" character with the "!" character.
Run it like this:
./replacestring.sh "?" "!"
This script saves you from removing multiple files unknowingly. It tells you how many files it will remove and asks you to confirm before removing them, if the number of files is more than 3.
If you've ever run rm text* and accidentally removed 100 files instead of the expected 5 files, this helps prevent that, by telling you exactly how many files will be removed first.
Run it like this, if for example you want to remove all files beginning with "text" in their filename:
./rmsafe.sh text*
This script swaps the contents of two files. For example, if you have files a.txt and b.txt, once you run it, a.txt will have the former b.txt content and b.txt will have the former a.txt content.
It doesn't check the file extensions so it's up to you to make sure you don't swap file.txt with image.png, but if you make a mistake you can always swap them back.
Run it like this:
./swapfiles.sh a.txt b.txt
This script prints out the current unix time.
Run it like this:
./unixtime.sh
This script uses the argument given as a filename, copies the contents of the clipboard to that filename, and then opens it in vim.
Run it like this, for a filename named copy.txt:
./vimclipboard.sh copy.txt
This script opens the last modified file in vim. Use it if you use vim as your regular editor.
Run it like this:
./vimlast.sh