Interactive mode for apropos/whatis.

[Kristaps Dzonsons <kristaps@bsd.lv>]

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Hi,

Let's be creative!  I've cooked up a tiny little patch that does the 
following.

(1) Add an `-I' mode to apropos.c (apropos/whatis).
(2) If `-I', prepend a choice number to each matching manual.
(3) If `-I', instead of returning, ask the user for their choice.
(4) Pipe result into MANPAGER/PAGER/more(1).

Or by way of example:

% MANPAGER=head ./whatis -I find
[1] File::Find(3p) - Traverse a directory tree.
[2] find(1) - walk a file hierarchy
[3] Pod::Find(3p) - find POD documents in directory trees
Choose a manual number: 2
FIND(1)               General Commands Manual              FIND(1)

NAME
      find -- walk a file hierarchy

SYNOPSIS
      find [-dHhLXx] [-f path] path ... [expression]

DESCRIPTION
      find recursively descends the directory tree for each path

Thoughts on this?  My reasoning was people will probably go from 
apropos/whatis into man anyway.  Might as well save them the trouble.

My original thought was to add a `man' mode, like `apropos', that 
stipulated Nm~^key$ and routes to the first option.  I went with the 
above route to avoid the sticky part of sorting output properly.  Of 
course, with a few hours of work, the `man' mode is quite possible. 
However, mandocdb(8) would need to respect the man.conf arguments more.

Thoughts?

Kristaps

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Index: apropos.c
===================================================================
RCS file: /usr/vhosts/mdocml.bsd.lv/cvs/mdocml/apropos.c,v
retrieving revision 1.24
diff -u -r1.24 apropos.c
--- apropos.c	12 Dec 2011 02:00:49 -0000	1.24
+++ apropos.c	14 Dec 2011 10:30:14 -0000
@@ -34,6 +34,7 @@
 static	void	 usage(void);
 
 static	char	*progname;
+static	int	 interactive;
 
 int
 main(int argc, char *argv[])
@@ -63,11 +64,14 @@
 	conf_file = NULL;
 	e = NULL;
 
-	while (-1 != (ch = getopt(argc, argv, "C:M:m:S:s:")))
+	while (-1 != (ch = getopt(argc, argv, "C:IM:m:S:s:")))
 		switch (ch) {
 		case ('C'):
 			conf_file = optarg;
 			break;
+		case ('I'):
+			interactive = 1;
+			break;
 		case ('M'):
 			defpaths = optarg;
 			break;
@@ -118,20 +122,78 @@
 	return(rc ? EXIT_SUCCESS : EXIT_FAILURE);
 }
 
-/* ARGSUSED */
 static void
 list(struct res *res, size_t sz, void *arg)
 {
-	int		 i;
+	int		 i, choice;
+	int		 fds[2];
+	char		*line;
+	const char	*cmd;
+	size_t		 linesz;
+	pid_t		 pid;
+
+	if (0 == sz) {
+		fprintf(stderr, "Nothing matched your search.\n");
+		return;
+	}
 
 	qsort(res, sz, sizeof(struct res), cmp);
 
-	for (i = 0; i < (int)sz; i++)
+	for (i = 0; i < (int)sz; i++) {
+		if (interactive)
+			printf("[%d] ", i + 1);
 		printf("%s(%s%s%s) - %s\n", res[i].title,
 				res[i].cat,
 				*res[i].arch ? "/" : "",
 				*res[i].arch ? res[i].arch : "",
 				res[i].desc);
+	}
+
+	if ( ! interactive)
+		return;
+
+	printf("Choose a manual number: ");
+
+	if (NULL != (line = fgetln(stdin, &linesz)) && 
+			linesz > 1 && '\n' == line[(int)linesz - 1]) {
+		line[(int)linesz - 1] = '\0';
+		choice = atoi(line);
+	} else
+		return;
+
+	if (choice < 1 || choice-- > (int)sz)
+		return;
+
+	cmd = getenv("PAGER");
+	if (getenv("MANPAGER"))
+		cmd = getenv("MANPAGER");
+	if (NULL == cmd)
+		cmd = "more";
+
+	if (0 == strcmp(res[choice].type, "cat")) {
+		execlp(cmd, cmd, res[choice].file, (char *)NULL);
+		perror(cmd);
+		return;
+	} 
+	
+	if (SIG_ERR == signal(SIGCHLD, SIG_IGN) ||
+			-1 == pipe(fds) || -1 == (pid = fork())) {
+		perror(NULL);
+		return;
+	} 
+	
+	if (pid > 0) {
+		close(fds[1]);
+		dup2(fds[0], STDIN_FILENO);
+		execlp(cmd, cmd, (char *)NULL);
+	} else {
+		close(fds[0]);
+		dup2(fds[1], STDOUT_FILENO);
+		cmd = "mandoc";
+		execlp(cmd, cmd, res[choice].file, (char *)NULL);
+	}
+
+	perror(cmd);
 }
 
 static int