Setting up your Mac for working on the command line.

Setting up your Mac for working on the command line.

• Time-stamp: <2018-11-06 09:32:33 tamara>
• published date: 2017-07
• keywords: command line, cli, termoial, mac

Before beginning, I strongly urge you to get Michael Hartl’s Learn Enough Command Line to Be Dangerous which is seriously the best introduction to this whole thing.

See also: [Conventions Used in This Section]({{ “/pages/learning/beginner/conventions-used-in-this-section”}}).

Intro

I’d love to provide the TL;DR for this, but I can’t. I don’t know what’s on your system already, what level you’re at, or even a kind voice to listen to your questions and respond.

Using the caommand line effectively means having it configured to your needs. So this page is going to introduce how to configure your command line.

There are two, sometimes three, files involved in this:

.bash_profile
.profile
.bashrc

The rest of this will tell you how to set them up.

You’ll need to know

• How to open Terminal on a Mac
• Various shell commands:

  cd
  chmod
  cp
  echo
  ls
  

Gathering Current Information

1. Open up the Terminal
2. Run the command:

ls -1 .profile .bash_profile .bashrc

The “-1” (“minus-one”) option produces a listing of file names in a single column. It’s not necessary, but it’s a little easier to read for short listings.

The ls command has lots of options which can be learned about using the man ls command and reading the manual page.

You could see something like the following:

ls: .bash_profile: No such file or directory
ls: .bashrc: No such file or directory
ls: .profile: No such file or directory

in which case you don’t have any of those files, which is okay.

You might see something like this:

ls: .bash_profile: No such file or directory
ls: .profile: No such file or directory
.bashrc

in which case you have the .bashrc file, but you don’t have the others, which is also okay.

In fact, any combination is okay, there’ll be a section below on each case.

Here are the combinations:

1. You don’t have any of them (default OSX setup)
2. You have .profile but not the other two
3. You have .bash_profile but not the other two
4. You have .bashrc but not the other two
5. You have .bash_profile and .bashrc , but not .profile
6. You have .profile and .bashrc , but not .bash_profile
7. You have all three

If you don’t have any of the three files

In this section, we’ll talk about when none of those files exist yet. This is easiest to deal with starting off.

What are the .bash_profile and .profile file about?

On Unix- and Linux-based systems, the command line is also referred to as “The Shell”. By default, Mac’s use the program “bash” as the command line shell.

When you start up Terminal, it launches a “login shell” by starting the program /bin/bash . This program then looks for two files in your user’s [home directory][homedir]: .bash_profile and .profile .

It’s important to note that if bash finds .bash_profile , it will run that file, otherwise it will run .profile . There may come a time when you install a software development command-line tool that creates a .bash_profile , and you can find all the things you put in .profile are not being set up. Likewise, you might install a software command line tool that only expects things to be initialized in .profile and then that tool’s setting won’t happen correctly. It’s confusing, to be sure.

There’s always more than one way to deal with this, of course. Perhaps the best way is to start with the .bash_profile and make all your initialisation happen there.

I prefer to do the following though:

1. Create a .bash_profile in your home directory with the following contents:

#!/bin/bash
[ -f $HOME/.profile ] && source $HOME/.profile

What this does is execute the .profile file if it exists. In this way you can have initialisation code put in either file and it will be run. The major caveat on this is to make sure if there’s initialisation code in both .bash_profile and .profile it does not cause any problems if it gets run twice. Usually this is okay, but it can be a source of errors.

1. Create the .profile file and place the initialisation codes you want to manage there.

The .profile file

As noted, this file contains initialisation codes. Here’s where you can set environment variables that are used throughout your command line sessions.

One such environment variable is PATH – this is the variable used to find command line programs on your computer. Sometimes you’ll need to extend this variable when you install a new piece of software.

Jump into your command line now and type:

$ echo $PATH

Incidently, that first “$” on the line above is not part of the command; it is there to indicate the command line prompt (which could be much more complicated). It’s used here to tell you something you should be typing. What you’ll actually type is what follows the space after the “$”, i.e. just “echo $PATH”.

On the stock Mac install, you’ll probably see something like:

/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin

(It might be slightly different, or it might have been changed previously.)

Let’s take the case where you just recently install the “Sass” program which pre-processed CSS files in a special format. After you’ve run the gem install sass --user-install command, you may have seen a warning like the following:

WARNING:  You don't have /Users/noob/.gem/ruby/2.0.0/bin in your PATH, gem executables will not run.

While not an error, not addressing this warning is going to be very painful for you.

So let’s add that indicated directory to our PATH environment variable. We do this in the .profile file like so:

export PATH=$PATH:$HOME/.gem/ruby/2.0.0/bin

Save and close your .profile file, switch back to your command line, and type the following:

$ source $HOME/.profile
$ echo $PATH

Now you should see the following:

usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Users/noob/.gem/ruby/2.0.0/bin

If you have .bash_profile , but none of the others

If you already have one, the easiest is to add the following line at the bottom of the file:

[ -f $HOME/.profile ] && source $HOME/.profile

then save and close the file.

Then open a new file named .profile and enter the following in it:

\#!/bin/bash

Then you can add whatever other initialisation codes you want in .profile . Follow the example in the previous section to append something to your PATH environment variable.

If you have .profile , but none of the others

Create a .bash_profile in your home directory with the following contents:

\#!/bin/bash
[ -f $HOME/.profile ] && source $HOME/.profile

That’s all, really.

If you do NOT have a .bashrc file

This is the default starting point for a new user.

What is the .bashrc file all about?

The .bashrc file in your home directory will be executed whenever an interactive shell gets invoked. Calling bash from the command line from a is considered an interactive shell. It is not run, however, when a login shell is started, which is what happens when you start up a new Terminal window.

Confusing? Yes. Try the following to see what is happening.

Edit your .profile and add the following line to the end:

echo ".profile ran"

Edit .bashrc (creating it if necessary) and put the following at the end:

echo ".bashrc ran"

Now open a new Terminal window (Command-N) and see what is printed. You should just see “.profile ran” before the prompt:

.profile ran
$

Your command prompt will be different of course.

Now run an interactive bash:

$ bash

You should now see something like:

.bashrc ran
bash-3.2$

You can see that the .bashrc file is not run on starting up a new window. (You might also see your command prompt change! We’ll fix that in a second.)

What we actually want usually, is to have the .bashrc file run for a login shell as well.

To do that, we need to fix up the .profile file with the following line at the end of the file:

[ -x $HOME/.bashrc ] && source $HOME/.bashrc

This will cause the .bashrc file to be executed at the end of the .profile file’s executing but only if the .bashrc file is executable .

This gives a little extra control, if we don’t want .bashrc to run at login, we can unset it’s execution bit. But for now, let’s set it:

$ chmod +x $HOME/.bashrc
$ ls -l .bashrc

And you should see something like:

\-rwxr-xr-x  1 noob  staff  32 Aug  7 01:01 .bashrc

Which shows it’s become executable for everyone on the system.

Close the Terminal window and open a new one. Now you should see the following before the first command line prompt:

.bashrc ran
.profile ran

You can remove those two “echo” commands from .profile and .bashrc if you wish, or leave them in as tracers while you’re working with them.

Creating the .bashrc file

This file initialized each interactive shell, including setting some environment variables used by bash , aliases, and other settings.

There is a global /etc/bashrc file that is a good starting point for your own.

Run the following command:

$ cp /etc/bashrc $HOME/.bashrc

This will overwrite the .bashrc file you just made, but that’s okay since there really wasn’t anything in it.

Give the new file execute permission:

$ chmod +x $HOME/.bashrc

Close the Terminal window and open a new one.

If you have .bashrc but neither .bash_profile or .profile

In this case, you want to add running the .bashrc file for login shells so those settings are available.

Add the following line to the end of your .profile :

[ -x $HOME/.bashrc ] && source $HOME/.bashrc

as in the previous section. You may need to set the execute bit on .bashrc as well:

$ chmod +x .bashrc

If you have .bashrc , and one or both of .bash_profile and .profile

If you only have one of .bash_profile or .profile see the appropriate section above.

Make sure one of those two files is calling .bashrc as in the previous section. If neither do, put the line into .profile .