In this tutorial I’ll show how to get some nicely colored man pages by
adding several lines inside the .bashrc file, explaining what the code
means and how it works.
Except for the eye-candy, colors may help when it comes to clarity,
although some prefer the default monochrome approach. At the start of
this article there is the actual code which can be copied and pasted
inside the ~/.bashrc file, and which can be modified depending on each
person’s preferences. If you don’t care about what it does you can just
insert it in ~/.bashrc, restart your terminal and start reading some man
pages to see how it looks (e.g. man man). After this part I tried to
explain how this code works and how to modify it in order to get new
‘themes’.
The code
For this tutorial we’ll be editing the ~/.bashrc file, which is a
hidden file located in your home directory which gets read each time a
new Bash instance starts up. Bash reads all the commands found in this
file and executes them (hence the
rc part, which stands for
run
commands).
We will edit this file and add some lines which specify certain colors for the $LESS_TERMCAP variables.
export LESS_TERMCAP_mb=$(printf '\e[01;31m') # enter blinking mode - red
export LESS_TERMCAP_md=$(printf '\e[01;35m') # enter double-bright mode - bold, magenta
export LESS_TERMCAP_me=$(printf '\e[0m') # turn off all appearance modes (mb, md, so, us)
export LESS_TERMCAP_se=$(printf '\e[0m') # leave standout mode
export LESS_TERMCAP_so=$(printf '\e[01;33m') # enter standout mode - yellow
export LESS_TERMCAP_ue=$(printf '\e[0m') # leave underline mode
export LESS_TERMCAP_us=$(printf '\e[04;36m') # enter underline mode - cyan
Don’t forget to reset your terminal after entering this code in order for the changes to take effect, e.g. type
reset or
exit and start up another shell.
This will mostly use magenta and cyan as the colors. Next, I’ll explain what these lines mean and how you can modify the colors.
Explaining it
As you can see, there are several variables which are assigned
different values. As shown in the comments after the # sign, every one
is used when needed. When text is in bold (double-bright mode), the
formatting option is set to bold and the color magenta.
Let’s take, for example, the following line:
export LESS_TERMCAP_md=$(printf '\e[01;35m') # enter double-bright mode - bold, magenta
This line could be broken into this:
- the environment variable LESS_TERMCAP_md will be assigned the value to the right of the equal sign
- the right side says execute the command between the $( and ) characters, just like the older ` ` did
- printf is a command similar with C’s printf and means “print
with format”. The characters between the double quotes specify a color
and a font style (e.g. in this case, bold and magenta).
The part that is inside the double quotes are format specifiers like
bold, regular, or color to be used. More on these can be found on
Wikipedia,
here.
Color codes
The color codes are as follows:
- 30 – black
- 31 – red
- 32 – green
- 33 – orange
- 34 – blue
- 35 – magenta
- 36 – cyan
- 37 – white
Some other escape codes which you could use include:
- 0 – reset/normal
- 1 – bold
- 3 – italic/reversed
- 4 – underlined
- 5 – blink
You can check this by typing in a terminal something like:
printf '\e[31m'
printf '\e[32m'
printf '\e[37m'
So, if we have something like
printf ‘\e[01;33m’ it means enter bold and color yellow, according to the listing above.
What about ‘export’?
export is a Bash built-in used to assign values to variables in
such a manner that any subsequent application that runs in that shell
will be aware of the variable’s value. If, for example, we would simply
assign a value to a variable, say
MYVAR=”this is my variable” and we would then issue
echo $MYVAR, we would see that the variable’s value will be printed. However, try to make a simple script which would echo it, for example:
#!/bin/bash
echo $MYVAR
And then run it e.g.
bash myscript.sh – you will see that the value is lost, not visible in the script. So this is where
export is useful, because it will make any further script or application “see” the variable. When we invoke the
man command, it will need to see the values for our LESS_TERMCAP variables.
More color schemes
Here is another color scheme:
export LESS_TERMCAP_mb=$(printf '\e[01;31m') # enter blinking mode
export LESS_TERMCAP_md=$(printf '\e[01;38;5;75m') # enter double-bright mode
export LESS_TERMCAP_me=$(printf '\e[0m') # turn off all appearance modes (mb, md, so, us)
export LESS_TERMCAP_se=$(printf '\e[0m') # leave standout mode
export LESS_TERMCAP_so=$(printf '\e[01;33m') # enter standout mode
export LESS_TERMCAP_ue=$(printf '\e[0m') # leave underline mode
export LESS_TERMCAP_us=$(printf '\e[04;38;5;200m') # enter underline mode
