Introduce the i3-sensible-{pager,editor,terminal} scripts

The former two provide fallbacks in case $PAGER or $EDITOR is not set (which
might be more common than you think, because they have to be set in
~/.xsession, not in the shell configuration!) while the latter tries to launch
a terminal emulator. The scripts are most prominently used in i3-nagbar, which
alerts the user when the configuration is broken for some reason. Also,
i3-sensible-terminal is used in the default configuration.

This commit does not rely on the shell supporting ${PAGER:-less} anymore, which
is not the case for 'fish'.

Makefile

@@ -80,6 +80,9 @@ install: all
 	$(INSTALL) -d -m 0755 $(DESTDIR)$(PREFIX)/share/xsessions
 	$(INSTALL) -m 0755 i3 $(DESTDIR)$(PREFIX)/bin/
 	$(INSTALL) -m 0755 i3-migrate-config-to-v4 $(DESTDIR)$(PREFIX)/bin/
+	$(INSTALL) -m 0755 i3-sensible-editor $(DESTDIR)$(PREFIX)/bin/
+	$(INSTALL) -m 0755 i3-sensible-pager $(DESTDIR)$(PREFIX)/bin/
+	$(INSTALL) -m 0755 i3-sensible-terminal $(DESTDIR)$(PREFIX)/bin/
 	test -e $(DESTDIR)$(SYSCONFDIR)/i3/config || $(INSTALL) -m 0644 i3.config $(DESTDIR)$(SYSCONFDIR)/i3/config
 	test -e $(DESTDIR)$(SYSCONFDIR)/i3/config.keycodes || $(INSTALL) -m 0644 i3.config.keycodes $(DESTDIR)$(SYSCONFDIR)/i3/config.keycodes
 	$(INSTALL) -m 0644 i3.welcome $(DESTDIR)$(SYSCONFDIR)/i3/welcome

PACKAGE-MAINTAINER

@@ -10,15 +10,21 @@ packages for them.
 Please make sure the manpage for i3 will be properly created and installed
 in your package.
 
-Also please provide the path to a suitable terminal emulator which is installed
+Please check the i3-sensible-{editor,pager,terminal} scripts and modify them if
-as a dependency of your package (e.g. urxvt). On systems which have a special
+necessary. The former two provide fallbacks in case $PAGER or $EDITOR is not
-commend to launch the best available terminal emulator, please use this one
+set (which might be more common than you think, because they have to be set in
-(e.g. x-terminal-emulator on debian).
+~/.xsession, not in the shell configuration!) while the latter tries to launch
+a terminal emulator. The scripts are most prominently used in i3-nagbar, which
+alerts the user when the configuration is broken for some reason. Also,
+i3-sensible-terminal is used in the default configuration.
 
-On debian, this looks like this:
+If your distribution has a mechanism to get the preferred terminal, such as the
+x-terminal-emulator symlink in Debian, please use it in i3-sensible-terminal.
+
+On debian, compilation and installing the manpages looks like this:
 
 	# Compilation
-	$(MAKE) TERM_EMU=x-terminal-emulator
+	$(MAKE)
 	$(MAKE) -C man
 
 	# Installation

common.mk

@@ -12,7 +12,6 @@ ifndef SYSCONFDIR
     SYSCONFDIR=$(PREFIX)/etc
   endif
 endif
-TERM_EMU=xterm
 # The escaping is absurd, but we need to escape for shell, sed, make, define
 GIT_VERSION:="$(shell git describe --tags --always) ($(shell git log --pretty=format:%cd --date=short -n1), branch $(shell [ -f $(TOPDIR)/.git/HEAD ] && sed 's/ref: refs\/heads\/\(.*\)/\\\\\\"\1\\\\\\"/g' $(TOPDIR)/.git/HEAD || echo 'unknown'))"
 VERSION:=$(shell git describe --tags --abbrev=0)

i3-sensible-editor

@@ -0,0 +1,14 @@
+#!/bin/sh
+# This script tries to exec an editor by trying some known editors if $EDITOR is
+# not set.
+#
+# Distributions/packagers can enhance this script with a
+# distribution-specific mechanism to find the preferred pager.
+which $VISUAL >/dev/null && exec $VISUAL "$@"
+which $EDITOR >/dev/null && exec $EDITOR "$@"
+
+# Hopefully one of these is installed (no flamewars about preference please!):
+which nano >/dev/null && exec nano "$@"
+which vim >/dev/null && exec vim "$@"
+which vi >/dev/null && exec vi "$@"
+which emacs >/dev/null && exec emacs "$@"

i3-sensible-pager

@@ -0,0 +1,15 @@
+#!/bin/sh
+# This script tries to exec a pager by trying some known pagers if $PAGER is
+# not set.
+#
+# Distributions/packagers can enhance this script with a
+# distribution-specific mechanism to find the preferred pager.
+which $PAGER >/dev/null && exec $PAGER "$@"
+
+# Hopefully one of these is installed:
+which most >/dev/null && exec most "$@"
+which less >/dev/null && exec less "$@"
+# we don't use 'more' because it will exit if the file is 'too short'
+
+# If no pager is installed, try an editor
+exec i3-sensible-editor "$@"

i3-sensible-terminal

@@ -0,0 +1,15 @@
+#!/bin/sh
+# This script tries to exec a terminal emulator by trying some known terminal
+# emulators.
+#
+# Distributions/packagers should enhance this script with a
+# distribution-specific mechanism to find the preferred terminal emulator. On
+# Debian, there is the x-terminal-emulator symlink for example.
+# Please don't touch the first line, though:
+which $TERMINAL >/dev/null && exec $TERMINAL "$@"
+
+# Hopefully one of these is installed:
+which xterm >/dev/null && exec xterm "$@"
+which urxvt >/dev/null && exec urxvt "$@"
+which rxvt >/dev/null && exec rxvt "$@"
+which roxterm >/dev/null && exec roxterm "$@"

i3.config

@@ -16,7 +16,7 @@ font -misc-fixed-medium-r-normal--13-120-75-75-C-70-iso10646-1
 floating_modifier Mod1
 
 # start a terminal
-bindsym Mod1+Return exec urxvt
+bindsym Mod1+Return exec i3-sensible-terminal
 
 # kill focused window
 bindsym Mod1+Shift+q kill

i3.config.keycodes

@@ -17,7 +17,7 @@ font -misc-fixed-medium-r-normal--13-120-75-75-C-70-iso10646-1
 floating_modifier $mod
 
 # start a terminal
-bindcode $mod+36 exec urxvt
+bindcode $mod+36 exec i3-sensible-terminal
 
 # kill focused window
 bindcode $mod+Shift+24 kill

src/cfgparse.y

@@ -276,9 +276,9 @@ static void start_configerror_nagbar(const char *config_path) {
     if (configerror_pid == 0) {
         char *editaction,
              *pageraction;
-        if (asprintf(&editaction, TERM_EMU " -e sh -c \"${EDITOR:-vi} \"%s\" && i3-msg reload\"", config_path) == -1)
+        if (asprintf(&editaction, "i3-sensible-terminal -e sh -c \"i3-sensible-editor \\\"%s\\\" && i3-msg reload\"", config_path) == -1)
             exit(1);
-        if (asprintf(&pageraction, TERM_EMU " -e sh -c \"${PAGER:-less} \"%s\"\"", errorfilename) == -1)
+        if (asprintf(&pageraction, "i3-sensible-terminal -e i3-sensible-pager \"%s\"", errorfilename) == -1)
             exit(1);
         char *argv[] = {
             NULL, /* will be replaced by the executable path */