bash lib : system out

system-out.bash

#!/bin/bash

[[ -z $DBG ]] && DBG=0

now() {
   date +"%Y-%m-%d %H:%M:%S"
}

eecho() {
    local label=$1
    shift
    local msg=
    if [[ $# == 0 ]]; then
        msg=$(cat -)
    else
        msg="$*"
    fi
    echo -e "$label : "$msg
}

dbg() {
  [[ $DBG == 1 ]] && (1>&2 eecho "[DEBUG]" $*)
}

info() {
  eecho "$(now)" $*
}

warn() {
  eecho "[WARN]" $*
}

err() {
  (1>&2 eecho "[ERROR]" $*)
}

Example of usage:

echo foo bar | info 
2017-05-25 14:33:26 : foo bar
info foo bar
2017-05-25 14:33:31 : foo bar
warn foo bar
[WARN] : foo bar
echo 'foo bar' | warn        
[WARN] : foo bar
dbg foo bar
DBG=1 dbg foo bar
[DEBUG] : foo bar
DBG=0 dbg foo bar
echo foo bar | DBG=1 dbg
[DEBUG] : foo bar