How to pass the redirection char ("<" and ">") to a command?

Question

I'm trying to figure out how I can make a script I'm running to be more readable. I have multiple commands which I would like to separate from the actual output.

My first thought was to use set -x, but this was still lost between the output of the actual commands. So I've found and applied two bash functions which I call before each function:

#!/usr/bin/env bash

function c_echo(){
    local color=$1;
    shift
    local exp=$@;
    if ! [[ $color =~ '^[0-9]$' ]] ; then
       case $(echo $color | tr '[:upper:]' '[:lower:]') in
        black) color=0 ;;
        red) color=1 ;;
        green) color=2 ;;
        yellow) color=3 ;;
        blue) color=4 ;;
        magenta) color=5 ;;
        cyan) color=6 ;;
        white|*) color=7 ;; # white or invalid color
       esac
    fi
    tput setaf $color;
    echo $exp;
    tput sgr0;
}

function script_cmd() {
    c_echo YELLOW "\$ $@";
    "$@";
}

export -f script_cmd
export -f c_echo

Later inside my script:

c_echo GREEN "1. Download insulin (2HIU) and Leucine zipper (2ZTA)."

script_cmd wget https://files.rcsb.org/view/2HIU.cif

This works perfectly, but fails on commands which actually do redirection. Is there a way I can work around this?

script_cmd charmm < setup_2zta.inp > setup_2zta.out

pynexj · Answer 1 · 2017-09-14T07:34:14.827

1

You can redirect the colorful output to stderr:

function script_cmd() {
    c_echo YELLOW "\$ $@" >&2
    #                     ^^^
    "$@";
}

If you want to colorize the whole charmm < setup_2zta.inp > setup_2zta.out command you can

script_cmd bash -c 'charmm < setup_2zta.inp > setup_2zta.out'

or

function script_cmd() {
    c_echo YELLOW "\$ $@" >&2
    #                     ^^^
    eval "$@";
    #^^^
}

script_cmd 'charmm < setup_2zta.inp > setup_2zta.out'

edited Sep 14 '17 at 07:34

answered Sep 14 '17 at 06:30

pynexj

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but I also have to pipe the input command too right? I think that is what's missing – Bartlomiej Lewandowski Sep 14 '17 at 06:36
sorry i don't understand what you mean. what do u mean by "pipe the input command"? – pynexj Sep 14 '17 at 06:57
do u mean you want to colorize the whole string of `"charmm < setup_2zta.inp > setup_2zta.out"`? – pynexj Sep 14 '17 at 06:59
well I want to print out the whole command, and run the command correctly. Not sure if running `script_cmd cat < "asdf"` will work – Bartlomiej Lewandowski Sep 14 '17 at 07:02
is "charmm < setup_2zta.inp > setup_2zta.out" the whole command? – pynexj Sep 14 '17 at 07:03
ok, I checked, and the pipe is redirected correctly to the command, but it's just not being printed correctly – Bartlomiej Lewandowski Sep 14 '17 at 07:05
I think this is the closest to what I need https://stackoverflow.com/questions/9340129/test-stdout-and-stderr-redirection-in-bash-script – Bartlomiej Lewandowski Sep 14 '17 at 07:30
updated the answer. and yes `[ -t 1 ]` is the correct way to disable color when outputting non-tty files. – pynexj Sep 14 '17 at 07:35

How to pass the redirection char ("<" and ">") to a command?

1 Answers1