#33 Only print resulting command if the output is being redirected

2 files changed, 18 insertions, 4 deletions

diff --git a/README.md b/README.md
index e69d22f..07ef6a5 100644
--- a/README.md
+++ b/README.md
@@ -35,6 +35,15 @@ You can override the default icons/glyphs by setting the appropriate GLYPH_ vari
 set $menu exec $term --class=launcher -e env GLYPH_COMMAND="" GLYPH_DESKTOP="" GLYPH_PROMPT="? " sway-launcher
 ```
 
+By default, the launcher will use a generic & WM-agnostic command to launch the selected program. 
+However, it will detect if its output is being piped to another program and merely print 
+the selected command in that case - instead of launching it by itself. You can use this to integrate the launcher with other tools.
+For example, if you wish to launch your programs with `swaymsg exec`, you can do that like this:
+
+```shell
+ swaymsg exec "$(./sway-launcher-desktop.sh)"
+```
+
 ### Setup a Terminal command
 Some of your desktop entries will probably be TUI programs that expect to be launched in a new terminal window. Those entries have the `Terminal=true` flag set and you need to tell the launcher which terminal emulator to use. Pass the `TERMINAL_COMMAND` environment variable with your terminal startup command to the script to use your preferred terminal emulator. The script will default to `$TERM -e`
 
diff --git a/sway-launcher-desktop.sh b/sway-launcher-desktop.sh
index e58c053..351aaa5 100755
--- a/sway-launcher-desktop.sh
+++ b/sway-launcher-desktop.sh
@@ -5,7 +5,7 @@
 shopt -s nullglob globstar
 set -o pipefail
 if ! { exec 0>&3; } 1>/dev/null 2>&1; then
-   exec 3>/dev/null # If file descriptor 3 is unused in parent shell, output to /dev/null
+  exec 3>/dev/null # If file descriptor 3 is unused in parent shell, output to /dev/null
 fi
 # shellcheck disable=SC2154
 trap 's=$?; echo "$0: Error on line "$LINENO": $BASH_COMMAND"; exit $s' ERR
@@ -293,6 +293,11 @@ readarray -d ${DEL} -t PROVIDER_ARGS <<<${PROVIDERS[${PARAMS[1]}]}
 COMMAND=${PROVIDER_ARGS[2]//\{1\}/${PARAMS[0]}}
 COMMAND=${COMMAND//\{2\}/${PARAMS[3]}}
 COMMAND=${COMMAND%%[[:space:]]}
-echo "Launching command: ${COMMAND}" >&3
-setsid /bin/sh -c "${COMMAND}"  >& /dev/null < /dev/null &
-sleep 0.01
+
+if [ -t 1 ]; then
+  echo "Launching command: ${COMMAND}" >&3
+  setsid /bin/sh -c "${COMMAND}" >&/dev/null </dev/null &
+  sleep 0.01
+else
+  echo "${COMMAND}"
+fi