Add purpose, flags and return value

debian/post.install.ovh.sh

@@ -1,5 +1,34 @@
 #!/bin/sh
 
+# Purpose {{{
+# This script should be called at the end of a OVH Debian installation
+#   1. Update APT repositories and install few dependencies.
+#   2. Umount and remove temp Logical Volume (with all free space).
+#   3. Allow SSH connection with a password for root.
+#   4. Download and extract a latecommand archive.
+#   5. Source /etc/os-release file to have $VERSION_CODENAME variable.
+#   6. Run last post-install script dedicated to Debian Codename.
+#
+# 2023-06-26
+# }}}
+# Flags {{{
+## Exit on error {{{
+set -o errexit
+## }}}
+## Exit on unset var {{{
+### Use "${VARNAME-}" to test a var that may not have been set
+set -o nounset
+## }}}
+## Pipeline command is treated as failed {{{
+### Not available in POSIX sh − https://github.com/koalaman/shellcheck/wiki/SC3040
+#set -o pipefail
+## }}}
+## Help with debugging {{{
+### Call the script by prefixing it with "TRACE=1 ./script.sh"
+if [ "${TRACE-0}" -eq 1 ]; then set -o xtrace; fi
+## }}}
+# }}}
+
 # Update repositories
 apt update
 # Install few dependencies
@@ -21,3 +50,5 @@ tar xzf /tmp/latecommand.tar.gz -C /tmp/
 ## Source /etc/os-release to get Debian codename
 . /etc/os-release
 /bin/sh /tmp/latecommand/post."${VERSION_CODENAME:=bookworm}".sh
+
+exit 0