Show a welcome text on interactive shells running on Silverblue hosts

The welcome text uses the OSC 8 [1] escape sequence to add a hyperlink
to the Silverblue documentation [2].

Silence a SC1003 [3] because the intention is to print the 'ESC \'
string terminator (or ST), and not escape a single quote.

[1] https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda
[2] https://docs.fedoraproject.org/en-US/fedora-silverblue/toolbox/
[3] https://github.com/koalaman/shellcheck/wiki/SC1003

https://github.com/debarshiray/toolbox/pull/127

meson.build

@@ -8,6 +8,8 @@ project(
 go_md2man = find_program('go-md2man')
 shellcheck = find_program('shellcheck', required: false)
 
+profiledir = get_option('profile_dir')
+
 systemd_dep = dependency('systemd')
 tmpfilesdir = systemd_dep.get_pkgconfig_variable('tmpfilesdir')
 
@@ -24,3 +26,4 @@ install_data(
 
 subdir('data')
 subdir('doc')
+subdir('profile.d')

meson_options.txt

@@ -0,0 +1,6 @@
+option(
+  'profile_dir',
+  description: 'Directory for profile.d files to be read by the shell on start-up',
+  type: 'string',
+  value: '/usr/share/profile.d'
+)

profile.d/meson.build

@@ -0,0 +1,10 @@
+toolbox_sh = files('toolbox.sh')
+
+if shellcheck.found()
+  test('shellcheck profile.d', shellcheck, args: ['--shell=sh', toolbox_sh])
+endif
+
+install_data(
+  toolbox_sh,
+  install_dir: profiledir,
+)

profile.d/toolbox.sh

@@ -0,0 +1,26 @@
+[ "$BASH_VERSION" != "" ] || [ "$ZSH_VERSION" != "" ] || return 0
+[ "$PS1" != "" ] || return 0
+
+toolbox_config="$HOME/.config/toolbox"
+host_welcome_stub="$toolbox_config/host-welcome-shown"
+
+if [ -f /run/ostree-booted ] \
+   && ! [ -f "$host_welcome_stub" ]; then
+    echo ""
+    echo "Welcome to Fedora Silverblue. This terminal is running on the"
+    echo "immutable host system. You may want to try out the Toolbox for a"
+    echo "more traditional environment that allows package installation"
+    echo "with DNF."
+    echo ""
+    printf "For more information, see the "
+    # shellcheck disable=SC1003
+    printf '\033]8;;https://docs.fedoraproject.org/en-US/fedora-silverblue/toolbox/\033\\documentation\033]8;;\033\\'
+    printf ".\n"
+    echo ""
+
+    mkdir -p "$toolbox_config"
+    touch "$host_welcome_stub"
+fi
+
+unset toolbox_config
+unset host_welcome_stub