Coloured line functions

This is a collection of shell functions which print coloured lines of text.

Coloured lines can make it easy to tell where a piece of text starts or ends.

Functions

These could be stand-alone scripts, however I found it easier to write them as functions and source them into my shell when it starts.

# Shell functions to emit coloured lines

function redline {
    printf "\e[0;1;37;41m%s\e[0K\e[0m\n" "$*"
}

function yellowline {
    printf "\e[0;30;43m%s\e[K\e[0m\n" "$*"
}

function blueline {
    printf "\e[0;1;37;44m%s\e[0K\e[0m\n" "$*"
}

function greenline {
    printf "\e[0;1;37;42m%s\e[0K\e[0m\n" "$*"
}

function cyanline {
    printf "\e[0;1;37;46m%s\e[0K\e[0m\n" "$*"
}

function purpleline {
    printf "\e[0;1;37;45m%s\e[0K\e[0m\n" "$*"
}

function whiteline {
    printf "\e[0;1;37;47m%s\e[0K\e[0m\n" "$*"
}

These functions work by printing ANSI Escape Codes to change the colour of the text printed after the code, and to clear the remainder of the line after the supplied string.

One thing to note is that the functions, as written above, will always print the codes to generate coloured lines. You can change them so that they only print the "colour codes" when run in a terminal, and print some kind of plain-text version, without the colour codes. As an example ...

function redline {
    if [[ -t 1 ]]
    then
        printf "\e[0;1;37;41m%s\e[0K\e[0m\n" "$*"
    else
        echo "***** $* *****"
    fi
}

fail Function

In many of my scripts, when an error occurs I want to draw the user's eye to it. I do this using the fail function, which is pretty simple - it uses redline to print the message it received in a red line, then exits from the script.

This function is useful within scripts, but you probably don't want to include it in your .bashrc file. If you were to type fail in a shell, it would print the message and then immediately exit from the shell.

function fail {
    redline "$@"
    exit 1
}