Use command -v (built-in) instead of which(1) (Thanks val)

fixes #1380

i3-sensible-editor

@@ -10,7 +10,7 @@
 
 # Hopefully one of these is installed (no flamewars about preference please!):
 for editor in $VISUAL $EDITOR nano vim vi emacs pico qe mg jed gedit mc-edit; do
-    if which $editor > /dev/null 2>&1; then
+    if command -v $editor > /dev/null 2>&1; then
         exec $editor "$@"
     fi
 done

i3-sensible-pager

@@ -12,7 +12,7 @@
 # We don't use 'more' because it will exit if the file is too short.
 # Worst case scenario we'll open the file in your editor.
 for pager in $PAGER less most w3m i3-sensible-editor; do
-    if which $pager > /dev/null 2>&1; then
+    if command -v $pager > /dev/null 2>&1; then
         exec $pager "$@"
     fi
 done

i3-sensible-terminal

@@ -9,7 +9,7 @@
 # distribution-specific mechanism to find the preferred terminal emulator. On
 # Debian, there is the x-terminal-emulator symlink for example.
 for terminal in $TERMINAL urxvt rxvt terminator Eterm aterm xterm gnome-terminal roxterm xfce4-terminal; do
-    if which $terminal > /dev/null 2>&1; then
+    if command -v $terminal > /dev/null 2>&1; then
         exec $terminal "$@"
     fi
 done