Add support for scroll(1)

Scroll is a program that stores all the lines of its child and be used in st as
a way of implementing scrollback.

This solution is much better than implementing the scrollback in st itself
because having a different program allows to use it in any other program
without doing modifications to those programs.

1 files changed, 10 insertions, 6 deletions

diff --git a/st.c b/st.c
index 3e48410..5f2352a 100644
--- a/st.c
+++ b/st.c
@@ -664,7 +664,7 @@ die(const char *errstr, ...)
 void
 execsh(char *cmd, char **args)
 {
-	char *sh, *prog;
+	char *sh, *prog, *arg;
 	const struct passwd *pw;
 
 	errno = 0;
@@ -678,13 +678,17 @@ execsh(char *cmd, char **args)
 	if ((sh = getenv("SHELL")) == NULL)
 		sh = (pw->pw_shell[0]) ? pw->pw_shell : cmd;
 
-	if (args)
+	if (args) {
 		prog = args[0];
-	else if (utmp)
-		prog = utmp;
-	else
+		arg = NULL;
+	} else if (scroll || utmp) {
+		prog = scroll ? scroll : utmp;
+		arg = scroll ? utmp : NULL;
+	} else {
 		prog = sh;
-	DEFAULT(args, ((char *[]) {prog, NULL}));
+		arg = NULL;
+	}
+	DEFAULT(args, ((char *[]) {prog, arg, NULL}));
 
 	unsetenv("COLUMNS");
 	unsetenv("LINES");