Make colours, escape sequences optional

Coloured output is tedious to parse, even unnecessary where the report
backend is not a terminal.

Signed-off-by: Peter <lusitania@users.noreply.github.com>

README.md

@@ -51,4 +51,10 @@ cd docker-bench-security
 sh docker-bench-security.sh
 ```
 
+Coloured output may be switched off to ease parsing:
+
+```sh
+sh docker-bench-security.sh -n |& grep '^\[WARN\]'
+```
+
 This script was build to be POSIX 2004 compliant, so it should be portable across any Unix platform.

docker-bench-security.sh

@@ -18,6 +18,9 @@
 this_path=$(abspath "$0")       ## Path of this file including filenamel
 myname=$(basename "${this_path}")     ## file name of this script.
 
+# Defaults
+set_colours default
+
 export PATH=/bin:/sbin:/usr/bin:/usr/local/bin:/usr/sbin/
 
 # Check for required program(s)
@@ -37,6 +40,7 @@ usage () {
   cat <<EOF
   usage: ${myname} [options]
 
+  -n           optional  Don't colourise results
   -h           optional  Print this help message
   -l PATH      optional  Log output in PATH
 EOF
@@ -49,6 +53,7 @@ while getopts hl: args
 do
   case $args in
   h) usage; exit 0 ;;
+  n) set_colour none;;
   l) logger="$OPTARG" ;;
   *) usage; exit 1 ;;
   esac

helper_lib.sh

@@ -46,3 +46,24 @@ get_command_line_args() {
         tr "\0" " " < /proc/"$PID"/cmdline
     done
 }
+
+# Set terminal colours used by functions in output_lib
+set_colours() {
+
+    case "$?" in
+        none)
+            bldred=
+            bldgrn=
+            bldblu=
+            bldylw=
+            txtrst=
+            ;;
+        default|*)
+            bldred='\033[1;31m'
+            bldgrn='\033[1;32m'
+            bldblu='\033[1;34m'
+            bldylw='\033[1;33m' # Yellow
+            txtrst='\033[0m'
+            ;;
+    esac
+}

output_lib.sh

@@ -1,9 +1,4 @@
 #!/bin/sh
-bldred='\033[1;31m'
-bldgrn='\033[1;32m'
-bldblu='\033[1;34m'
-bldylw='\033[1;33m' # Yellow
-txtrst='\033[0m'
 
 logit () {
   printf "%b\n" "$1" | tee -a "$logger"