How do I get a list of running applications by using the command line?

A combination of wmctrl and xprop offers many possibilities.

Example 1:

running_gui_apps() {

    # loop through all open windows (ids)
    for win_id in $( wmctrl -l | cut -d' ' -f1 ); do 

        # test if window is a normal window
        if  $( xprop -id $win_id _NET_WM_WINDOW_TYPE | grep -q _NET_WM_WINDOW_TYPE_NORMAL ) ; then 

            echo "$( xprop -id $win_id WM_CLASS | cut -d" " -f4- )"", window id: $win_id"

        fi

    done
}

The output could look in this case similar like this:

"Firefox", window id: 0x032000a9
"Gnome-terminal", window id: 0x03a0000c
"Thunar", window id: 0x03600004
"Geany", window id: 0x03c00003
"Thunar", window id: 0x0360223e
"Mousepad", window id: 0x02c00003
"Mousepad", window id: 0x02c00248
"Xfce4-terminal", window id: 0x03e00004

Example 2:

running_gui_apps() {
    applications=()

    # loop through all open windows (ids)
    for win_id in $( wmctrl -l | cut -d' ' -f1 ); do 

        # test if window is a normal window
        if  $( xprop -id $win_id _NET_WM_WINDOW_TYPE | grep -q _NET_WM_WINDOW_TYPE_NORMAL ) ; then 

            # filter application name and remove double-quote at beginning and end
            appname=$( xprop -id $win_id WM_CLASS | cut -d" " -f4 )
            appname=${appname#?}
            appname=${appname%?}

            # add to result list
            applications+=( "$appname" ) 

        fi

    done

    # sort result list and remove duplicates  
    readarray -t applications < <(printf '%s\0' "${applications[@]}" | sort -z | xargs -0n1 | uniq)

    printf -- '%s\n' "${applications[@]}" 
}

Output example:

Firefox
Geany
Gnome-terminal
Mousepad
Thunar
Xfce4-terminal

You can add the function to your ~/.bashrc or run it from an script file.

Introduction

The power of xdotool and wmctrl comes out when you need to perform manipulation on the windows, such as moving or resizing. However, I strongly believe that for the purpose of only listing running programs and information about them, xprop and qdbus are two sufficient tools and installing xdotool and wmctrl unless the user wants those for additional functionality - is a purposeless task. In this answer I would like to present two scripting solutions with xprop and qdbus.

Note that I am by no means against xdotool or wmctrl. I've used them extensively myself , but I find them more powerful when combined with other tools. Here are just a few examples where I've used them :

• Creating workspace-dependent shortcut
• Moving all windows from one workspace to another

Xprop

The script bellow uses only xprop to extract list of the active windows , filter out only true windows ( not dock type suck as Unity Launcher or Unity Panel ) and display their info:

Demo:

$ bash xprop_windows.sh                                                        
XID TYPE    TITLE
--------------------------------

56623112| "x-terminal-emulator", "X-terminal-emulator"| "sakura"

81789126| "Navigator", "Firefox"| "Restore Session - Mozilla Firefox"

82002372| "Navigator", "Firefox"| "gui - How do I get a list of running applications by using the command line? - Ask Ubuntu - Mozilla Firefox"

33554444| "gnome-terminal", "Gnome-terminal"| "\"Terminal\""

33554486| "gnome-terminal", "Gnome-terminal"| "\"Terminal\""

Script source:

get_hex_xids()
{
xprop -root -notype _NET_CLIENT_LIST | \
     awk 'BEGIN{printf "ibase=16"}\
     {gsub(/\,/," ");for(i=1;i<=NF;i++) \
     if ($i~/0x/) printf ";%s",substr(toupper($i),3)   }'  
}

convert_hex2dec()
{
  HEXIDS=$(get_hex_xids)
  echo $HEXIDS | bc
}

print_header()
{
  printf "%s\t%s\t%s\n" "XID" "TYPE" "TITLE"
  printf "%s\n" "--------------------------------"
}

list_info()
{
  convert_hex2dec | while read line;
  do
  TYPE=$( xprop -id $line _NET_WM_WINDOW_TYPE | awk -F '=' '{print $2}'   )
  if [ $TYPE != "_NET_WM_WINDOW_TYPE_NORMAL"   ]; then
     continue
  fi
  CLASS=$(xprop -id $line WM_CLASS | awk -F '=' '{print $2}' )
  NAME=$( xprop -id $line _NET_WM_NAME | awk -F '=' '{print $2}'   )
  printf "\n%s|%s|%s\n" "$line" "$CLASS" "$NAME"

  done
}
print_header
list_info

Qdbus

The code bellow performs essentially the same task, however it filters out applications first, then lists its children windows , and finally provides info about them.

Sample run:

$ bash ~/bin/qdbus_windows.sh                                                  
Name: Terminal
Active :false
Children:
33554486|false|""Terminal""
33554444|false|""Terminal""
--------------
Name: Firefox Web Browser
Active :false
Children:
82002372|false|"gui - How do I get a list of running applications by using the command line? - Ask Ubuntu - Mozilla Firefox"
81789126|false|"Restore Session - Mozilla Firefox"
--------------
Name: MY CUSTOM TERMINAL
Active :true
Children:
56623112|true|"sakura"
--------------

Code itself:

#!/bin/bash

get_window_paths()
{
  qdbus org.ayatana.bamf  /org/ayatana/bamf/matcher org.ayatana.bamf.matcher.WindowPaths
}

get_running_apps()
{
  qdbus org.ayatana.bamf /org/ayatana/bamf/matcher org.ayatana.bamf.matcher.RunningApplications
}

list_children()
{
 qdbus org.ayatana.bamf "$1"  org.ayatana.bamf.view.Children
}

window_info()
{
for window in "$@" ; do
 XID=${window##*/}
 TYPE=$(qdbus org.ayatana.bamf $window org.ayatana.bamf.window.WindowType)                                         
 NAME="$(qdbus org.ayatana.bamf $window org.ayatana.bamf.view.Name)"
 ACTIVE=$(qdbus org.ayatana.bamf $window org.ayatana.bamf.view.IsActive)
 MONITOR=$(qdbus org.ayatana.bamf $window org.ayatana.bamf.window.Monitor)
# printf "%s|%s|%s|%s\n" $TYPE $MONITOR $ACTIVE "$NAME" 
 printf "%s|%s|\"%s\"\n" $XID $ACTIVE "$NAME" 
done
}

window_paths=( $( get_window_paths | tr '\n' ' ') )
apps_list=( $( get_running_apps | tr '\n' ' ' ) )

for app in ${apps_list[@]} ; do
#echo $app
  printf "Name: "
  qdbus org.ayatana.bamf $app org.ayatana.bamf.view.Name
  printf "Active :"
  qdbus org.ayatana.bamf $app org.ayatana.bamf.view.IsActive
  printf "Children:\n"
#  list_children $app
  windows=( $( list_children $app | tr '\n' ' ' ) )
  window_info "${windows[@]}"
  printf "%s\n"  "--------------"
done

A bit simpler command but requires filtering out the output uses Unity's window stack dbus interface. Here is essentially a function I have in my .mkshrc

window_stack()
{
  qdbus --literal com.canonical.Unity.WindowStack  
        /com/canonical/Unity/WindowStack  \
        com.canonical.Unity.WindowStack.GetWindowStack | \
  awk -F '{' '{gsub(/\}|\]|,/,"");gsub(/\[/,"\n");print $2}' | \
  awk '!/compiz/&&!/^$/ && $4!="\""$3"\""  { L[n++] = $0 }\
       END { while(n--) print L[n] }'
}

Sample run:

$ window_stack
Argument: (usbu) 56623112 "x-terminal-emulator" true 0 
Argument: (usbu) 82002372 "firefox" false 0 
Argument: (usbu) 81789126 "firefox" false 0 
Argument: (usbu) 33554486 "gnome-terminal" false 0 
Argument: (usbu) 33554444 "gnome-terminal" false 0

Examples of qdbus usage:

• Finding gnome-terminal's focused window and its pid

wmctrl -l could be a thing you wanted. First install it

sudo apt-get install wmctrl

You can also combine it with System Monitor's list, by default it shows "All my processes" which means all process that belong to you as a user.

To have only names of applications, run:

EDIT:

wmctrl -l|awk '{$3=""; $2=""; $1="";  print $0}'