add info manual

Signed-off-by: Mattias Andrée <maandree@member.fsf.org>

1 files changed, 31 insertions, 0 deletions

diff --git a/doc/info/chap/invoking.texinfo b/doc/info/chap/invoking.texinfo
new file mode 100644
index 0000000..53fae77
--- /dev/null
+++ b/doc/info/chap/invoking.texinfo
@@ -0,0 +1,31 @@
+@node Invoking
+@chapter Invoking
+
+@command{vtchs} ignores the command line
+and the environment variables. You cannot
+control its behaviour.
+
+However, it is required that standard input
+is a @file{/dev/tty} device. If this programs
+is running under root,
+@example
+vtchs < /dev/tty1
+@end example
+@noindent
+is sufficient. Non-root users need to find
+a TTY that they have access to. If your
+shell is GNU Bash, you can use
+@example
+vtchs < "/dev/tty$( i=1;
+                    while true; do
+                      if ! test -e /dev/tty$i; then
+                        exit 1;
+                      fi;
+                      exec < /dev/tty$i &&
+                      echo $i &&
+                      exit 0 ||
+                      : $(( i++ ));
+                    done 2>/dev/null
+                  )"
+@end example
+