diff --git a/bash-completion-generator-ivpn-cli.sh b/bash-completion-generator-ivpn-cli.sh
old mode 100644
new mode 100755
index 85ca480..5474324
--- a/bash-completion-generator-ivpn-cli.sh
+++ b/bash-completion-generator-ivpn-cli.sh
@@ -1,40 +1,62 @@
 #!/bin/bash
 
-# Generates a bash completion file for the `ivpn` CLI.
-# 
+# Bash completion generator for ivpn CLI
+# (generates a bash completion script for the `ivpn` CLI)
+# https://github.com/jordan-ivpn/bash-completion-generator-ivpn-cli/
+#
 # Usage:
-# Install the ivpn CLI package first: https://www.ivpn.net/apps-linux/
+#   Install the ivpn CLI package first: https://www.ivpn.net/apps-linux/
+#
+#   $ bash-completion-generator-ivpn-cli.sh > ivpn.bash
+#   $ source ivpn.bash
+#   $ sudo mv ivpn.bash /usr/share/bash-completion/completions/ivpn
+#   $ sudo chown root:root /usr/share/bash-completion/completions/ivpn
 #
-# $ bash-completion-generator-ivpn-cli.sh > ivpn.bash
-# $ source ivpn.bash
-# $ sudo mv ivpn.bash /usr/share/bash-completion/completions/ivpn
-# $ sudo chown root:root /usr/share/bash-completion/completions/ivpn
+# Info: 
+#   1)  The recommended directory is `completionsdir`, which you can get with `pkg-config --variable=completionsdir bash-completion`
+#       https://github.com/scop/bash-completion
+#
+
+# exit on error
+set -e
+
+# By default, the source command is `ivpn`. 
+# Also you can specify custom path to IVPN CLI binary in the first argument to this script (e.g. `bash-completion-generator-ivpn-cli.sh /usr/local/bin/ivpn`)
+cli="ivpn"
+if [ ! -z "$1" ]
+then
+  cli="$1"
+fi
+
+# Check if the command/binary exists
+if ! command -v "$cli" > /dev/null 2>&1; then
+    echo "Error: $cli not found or not executable"
+    exit 1
+fi
 
 # print header
 echo "# bash completion for ivpn"
 echo ""
 echo "_ivpn()"
 echo "{"
-echo '    local cur prev opts base'
+echo '    local cur opts'
 echo '    COMPREPLY=()'
-echo '    cur="${COMP_WORDS[COMP_CWORD]}"'
-echo '    prev="${COMP_WORDS[COMP_CWORD-1]}"'
+echo '    cur="${COMP_WORDS[COMP_CWORD]}" # current word'
+echo '    cmd="${COMP_WORDS[1]}"          # next word after "ivpn", e.g.: $ ivpn <cmd> ...'
 echo ""
 
-
 # determine command list and print list
 # first awk bit from: https://stackoverflow.com/a/22222219
-COMMAND_LIST=$(ivpn -h | grep -Ev ^$ | awk '/Tips:/{f=0} f; /COMMANDS:/{f=1}' | awk '{ print $1 }')
+COMMAND_LIST=$( $cli -h | grep -Ev ^$ | awk '/Tips:/{f=0} f; /COMMANDS:/{f=1}' | awk '{ print $1 }')
 
 echo "    opts="'"'$COMMAND_LIST" -h"'"'
 echo ""
-echo '    case "${prev}" in'
-
+echo '    case "${cmd}" in'
 
 # iterate over commands and print case entries for sub-commands
 for i in $COMMAND_LIST; do
     echo "        "$i")"
-    SUB_LIST=$(ivpn $i -h | grep -E '^  -' | awk '{ print $1 }' | tr "|" " ")
+    SUB_LIST=$($cli $i -h | grep -E '^  -' | awk '{ print $1 }' | tr "|" " ")
     echo "            local "$i"_opts="'"'$SUB_LIST" -h"'"'
     echo "            COMPREPLY=( \$(compgen -W "'"'"\${"$i"_opts}"'"'" -- \${cur}) )"
     echo "            return 0"