bin/ovr: -n, --lines: Add option to control permanent lines

This was previously accepted as a positional argument, but an option is
more conventional.  Use the same option name as tail(1), since we just
pass it directly to tail(1).

Rename the old $lines variable to $permanent, to avoid confusion.

Signed-off-by: Alejandro Colomar <alx@kernel.org>

1 files changed, 33 insertions, 4 deletions

diff --git a/bin/ovr b/bin/ovr
index f5c4feb..349bca3 100755
--- a/bin/ovr
+++ b/bin/ovr
@@ -2,14 +2,43 @@
 
 trap '' INT;
 
+
+err()
+{
+	>&2 echo "$(basename "$0"): error: $*";
+	exit 1;
+}
+
+
+n=1
+while test $# -ge 1; do
+	case "$1" in
+	-n | --lines)
+		if test $# -lt 2; then
+			err "$1: Missing option argument.";
+		fi;
+		n="$2";
+		shift;
+		;;
+	-*)
+		err "$1: Unknown option.";
+		;;
+	*)
+		err "$1: Unknown argument.";
+		;;
+	esac;
+	shift;
+done;
+
+
+permanent=;
+
 enter() { setterm --linewrap off; tput smcup; } >/dev/tty;
 leave() { setterm --linewrap on; tput rmcup; } >/dev/tty;
 
 trap leave QUIT TERM;
 
-lines=;
-n="${1:-1}";
 enter;
-lines="$(tee /dev/tty | tail -n "$n"; echo x)";
+permanent="$(tee /dev/tty | tail -n "$n"; echo x)";
 leave;
-printf '%s' "${lines%x}";
+printf '%s' "${permanent%x}";