Implement `set +o', which displays the currently set options in a format

suitable for re-input into the shell.

2 files changed, 28 insertions, 5 deletions

diff --git a/bin/sh/options.c b/bin/sh/options.c
index dbcb67e..07ca3db 100644
--- a/bin/sh/options.c
+++ b/bin/sh/options.c
@@ -200,13 +200,28 @@ options(int cmdline)
 STATIC void
 minus_o(char *name, int val)
 {
-	int i;
+	int doneset, i;
 
 	if (name == NULL) {
-		out1str("Current option settings\n");
-		for (i = 0; i < NOPTS; i++)
-			out1fmt("%-16s%s\n", optlist[i].name,
-				optlist[i].val ? "on" : "off");
+		if (val) {
+			/* "Pretty" output. */
+			out1str("Current option settings\n");
+			for (i = 0; i < NOPTS; i++)
+				out1fmt("%-16s%s\n", optlist[i].name,
+					optlist[i].val ? "on" : "off");
+		} else {
+			/* Output suitable for re-input to shell. */
+			for (doneset = i = 0; i < NOPTS; i++)
+				if (optlist[i].val) {
+					if (!doneset) {
+						out1str("set");
+						doneset = 1;
+					}
+					out1fmt(" -o %s", optlist[i].name);
+				}
+			if (doneset)
+				out1c('\n');
+		}
 	} else {
 		for (i = 0; i < NOPTS; i++)
 			if (equal(name, optlist[i].name)) {
diff --git a/bin/sh/sh.1 b/bin/sh/sh.1
index 8518687..a5c61e8 100644
--- a/bin/sh/sh.1
+++ b/bin/sh/sh.1
@@ -301,6 +301,14 @@ command line editor:
 set -E
 set -o emacs
 .Ed
+.Pp
+If used without an argument, the
+.Fl o
+option displays the current option settings in a human-readable format.
+If
+.Cm +o
+is used without an argument, the current option settings are output
+in a format suitable for re-input into the shell.
 .Ss Lexical Structure
 The shell reads input in terms of lines from a file and breaks
 it up into words at whitespace (blanks and tabs), and at