Add a naive /bin/fgrep for testing pipes.

Userland/.gitignore

@@ -19,3 +19,4 @@ tty
 ft
 ft2
 strsignal
+fgrep

Userland/Makefile

@@ -17,6 +17,7 @@ OBJS = \
        ft.o \
        ft2.o \
        strsignal.o \
+       fgrep.o \
        tty.o
 
 APPS = \
@@ -38,6 +39,7 @@ APPS = \
        ft \
        ft2 \
        strsignal \
+       fgrep \
        tty
 
 ARCH_FLAGS =
@@ -70,6 +72,9 @@ ps: ps.o
 ls: ls.o
 	$(LD) -o $@ $(LDFLAGS) $< ../LibC/LibC.a
 
+fgrep: fgrep.o
+	$(LD) -o $@ $(LDFLAGS) $< ../LibC/LibC.a
+
 sleep: sleep.o
 	$(LD) -o $@ $(LDFLAGS) $< ../LibC/LibC.a
 

Userland/fgrep.cpp

@@ -0,0 +1,20 @@
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+int main(int argc, char** argv)
+{
+    if (argc < 2) {
+        printf("usage: fgrep <str>\n");
+        return 0;
+    }
+    for (;;) {
+        char buf[4096];
+        fgets(buf, sizeof(buf), stdin);
+        if (feof(stdin))
+            return 0;
+        if (strstr(buf, argv[1]))
+            write(1, buf, strlen(buf));
+    }
+    return 0;
+}