agetty: add support for /etc/issue.d

The /etc/issue file has been originally designed to inform users
about the system (version, name, etc.).

In last years is growing number of additional tools (containers,
maintenance tools and interfaces, ...) and many admins and downstream
maintainer want to add some tool specific hints to the issue file, but
it mess to share one file between more packages and/or scripts. The
solution is /etc/issue.d directory.

The directory is extension to the standard system /etc/issue. The
/etc/issue file has to exist, otherwise the directory will be ignored.
It means "rm /etc/issue" (or --onissue) is still the way how keep our
system silent independently on 3rd-party installed files in the
/etc/issue.d directory.

The content of the files in the directory are printed after content of
the /etc/issue. The files are printed in version-sort order and .issue
file extension is required (00-foo.issue 01-bar.issue ...).

The change is backwardly compatible.

Signed-off-by: Karel Zak <kzak@redhat.com>

1 files changed, 21 insertions, 8 deletions

diff --git a/term-utils/agetty.8 b/term-utils/agetty.8
index f21634494..96d94bb48 100644
--- a/term-utils/agetty.8
+++ b/term-utils/agetty.8
@@ -32,7 +32,7 @@ Optionally does not hang up when it is given an already opened line
 .IP \(bu
 Optionally does not display the contents of the \fI/etc/issue\fP file.
 .IP \(bu
-Optionally displays an alternative issue file instead of \fI/etc/issue\fP.
+Optionally displays an alternative issue file or directory instead of \fI/etc/issue\fP or \fI/etc/issue.d\fP.
 .IP \(bu
 Optionally does not ask for a login name.
 .IP \(bu
@@ -113,10 +113,12 @@ is added to the \fB/bin/login\fP command line.
 .IP
 See \fB\-\-login\-options\fR.
 .TP
-\-f, \-\-issue\-file \fIissue_file\fP
-Display the contents of \fIissue_file\fP instead of \fI/etc/issue\fP.
-This allows custom messages to be displayed on different terminals.
-The \-\-noissue option will override this option.
+\-f, \-\-issue\-file \fIfile|directory\fP
+Display the contents of \fIfile\fP instead of \fI/etc/issue\fP.  If the
+specified path is a \fIdirectory\fP then displays all files with .issue file
+extension in version-sort order from the directory.  This allows custom
+messages to be displayed on different terminals.  The
+\-\-noissue option will override this option.
 .TP
 \-h, \-\-flow\-control
 Enable hardware (RTS/CTS) flow control.  It is left up to the
@@ -337,9 +339,20 @@ Some  programs use "\-\-" to indicate that the rest of the commandline should
 not be interpreted as options.  Use this feature if available by passing "\-\-"
 before the username gets passed by \\u.
 
-.SH ISSUE ESCAPES
-The issue-file (\fI/etc/issue\fP, or the file set with the \fB\-\-issue\-file\fP option)
-may contain certain escape codes to display the system name, date, time
+.SH ISSUE FILES
+The default issue file is \fI/etc/issue\fP. If the file exists then agetty also
+checks for \fI/etc/issue.d\fP directory. The directory is optional extension to
+the default issue file and content of the directory is printed after
+\fI/etc/issue\fP content. If the \fI/etc/issue\fP does not exist than the
+directory is ignored. All files with .issue extension from the directory are
+printed in version-sort order. The directory allow to maintain 3rd-party
+messages independently on the primary system \fI/etc/issue\fP file.
+
+The default path maybe overrided by \fB\-\-issue\-file\fP option. In this case
+specified path has to be file or directory and the default \fI/etc/issue\fP as
+well as \fI/etc/issue.d\fP are ignored.
+
+The issue files may contain certain escape codes to display the system name, date, time
 etcetera.  All escape codes consist of a backslash (\\) immediately
 followed by one of the characters listed below.