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unixsyntax-highlightingcolor-scheme

Syntax highlighting/colorizing cat


Is there a method to colorize the output of cat, the way grep does.

For grep, in most consoles it displays a colored output highlighting the searched keywords. Otherwise, you can force it by calling grep --color Is there a generic way to color the output of any program according to your personal choice.

From what I understand, the program itself is not responsible for the colors. It is the shell.

I am using the default shell in FreeBSD 5.2.1 which looks like it has never seen colors since epoch.


Solution

  • cat with syntax highlighting is simply out of scope. cat is not meant for that. If you just want to have the entire content of some file coloured in some way (with the same colour for the whole file), you can make use of terminal escape sequences to control the color.

    Here's a sample script that will choose the colour based on the file type (you can use something like this instead of invoking cat directly):

    #!/bin/bash
    fileType="$(file "$1" | grep -o 'text')"
    if [ "$fileType" == 'text' ]; then
        echo -en "\033[1m"
    else
        echo -en "\033[31m"
    fi
    cat $1
    echo -en "\033[0m"
    

    The above (on a terminal that supports those escape sequences) will print any text file as 'bold', and will print any binary file as red. You can use strings instead of cat for printing binary files and you can enhance the logic to make it suit your needs.