How do I change the default for the “df” command in unix/linux?

Question

I'm trying to change a default for the df command.

When I type the df command, I see the amount of disk free space listed in kilobytes. I want to change the default so that when I type in df alone, I will see the disk free space in Megabytes.

I already know that when I type df -m or df -h I will see it in megabytes, but I strictly just want to type in df so that I can see the values in megabytes.

If I can get a step by step on how to make this possible on changing the default for the df command to megabytes, I would love that. I was told that command line flags also could affect how this command could work, so I would also like clarification on that as well.

Answer 1

There is a file in your home directory called .bashrc which is executed every time you open a new terminal. In nautilus (the default graphical file browser) you will need to press Ctl+H to see files that start with a .

You can create "aliases" in this file, they will act as commands at the terminal. Edit .bashrc and add alias df="df -m" on its own line, probably best to put this at the top or bottom with a comment above it along the lines of #I added this line to change the behaviour of df.

Open a new terminal and df will now be df -m by default.

N.b. To use df normally you must now type \df

Answer 2

Like ls -s, df honors the BLOCKSIZE environmental variable. Put

BLOCKSIZE=1m
export BLOCKSIZE

into the .profile file in your home directory and when you next login df will report disk capacity and availability in megabytes.

If you're using tcsh instead of bash or sh as your shell, put

setenv BLOCKSIZE 1m

into .login in your home directory.