Implement grep -F

grep.1

@@ -3,7 +3,7 @@
 grep \- search files for a pattern
 .SH SYNOPSIS
 .B grep
-.RB [ \-EHchilnqsv ]
+.RB [ \-EFHchilnqsv ]
 .RB [ \-e
 .I pattern ]
 .I pattern
@@ -22,14 +22,18 @@ status code is 2.
 .SH OPTIONS
 .TP
 .B \-E
-matches using extended regex.
+Matches using extended regex.
+.TP
+.B \-F
+Match using fixed strings.  Treat each pattern specified as a string instead of a regular
+expression.
 .TP
 .B \-H
-prefixes each matching line with its filename in the output. This is the
+Prefixes each matching line with its filename in the output. This is the
 default when there is more than one file specified.
 .TP
 .B \-c
-prints only a count of matching lines.
+Prints only a count of matching lines.
 .TP
 .B \-e pattern
 Specify a pattern used during the search of the input: an input
@@ -39,26 +43,26 @@ specify multiple patterns, or when a pattern begins with a dash
 (`-').
 .TP
 .B \-h
-do not prefix each line with 'filename:' prefix.
+Do not prefix each line with 'filename:' prefix.
 .TP
 .B \-i
-matches lines case insensitively.
+Matches lines case insensitively.
 .TP
 .B \-l
-prints only the names of files with matching lines.
+Prints only the names of files with matching lines.
 .TP
 .B \-n
-prefixes each matching line with its line number in the input.
+Prefixes each matching line with its line number in the input.
 .TP
 .B \-q
-prints nothing, only returns status.
+Prints nothing, only returns status.
 .TP
 .B \-s
 Suppress the error messages ordinarily written for nonexistent or unreadable files.
 .TP
 .B \-v
-selects lines which do
+Selects lines which do
 .B not
-match the pattern.
+Match the pattern.
 .SH SEE ALSO
 .IR regex (7)

grep.c

@@ -14,6 +14,7 @@ enum { Match = 0, NoMatch = 1, Error = 2 };
 static void addpattern(const char *);
 static int grep(FILE *, const char *);
 
+static int Fflag;
 static int Hflag;
 static int eflag;
 static int hflag;
@@ -33,7 +34,7 @@ static SLIST_HEAD(phead, pattern) phead;
 static void
 usage(void)
 {
-	enprintf(Error, "usage: %s [-EHcilnqsv] [-e pattern] pattern [files...]\n", argv0);
+	enprintf(Error, "usage: %s [-EFHcilnqsv] [-e pattern] pattern [files...]\n", argv0);
 }
 
 int
@@ -49,6 +50,9 @@ main(int argc, char *argv[])
 	case 'E':
 		flags |= REG_EXTENDED;
 		break;
+	case 'F':
+		Fflag = 1;
+		break;
 	case 'H':
 		Hflag = 1;
 		break;
@@ -88,6 +92,7 @@ main(int argc, char *argv[])
 		argv++;
 	}
 
+	if (!Fflag)
 		/* Compile regex for all search patterns */
 		SLIST_FOREACH(pnode, &phead, entry)
 			enregcomp(Error, &pnode->preg, pnode->pattern, flags);
@@ -111,6 +116,7 @@ main(int argc, char *argv[])
 	while (!SLIST_EMPTY(&phead)) {
 		pnode = SLIST_FIRST(&phead);
 		SLIST_REMOVE_HEAD(&phead, entry);
+		if (!Fflag)
 			regfree(&pnode->preg);
 		free(pnode->pattern);
 		free(pnode);
@@ -142,8 +148,15 @@ grep(FILE *fp, const char *str)
 		if (len && buf[len - 1] == '\n')
 			buf[len - 1] = '\0';
 		SLIST_FOREACH(pnode, &phead, entry) {
+			if (!Fflag) {
 				if (regexec(&pnode->preg, buf, 0, NULL, 0) ^ vflag)
 					continue;
+			} else {
+				match = strstr(buf, pnode->pattern) ? Match : NoMatch;
+				match ^= vflag;
+				if (match)
+					continue;
+			}
 			switch (mode) {
 			case 'c':
 				c++;