--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toys/pidof.c	Sat Feb 18 15:08:31 2012 -0600
@@ -0,0 +1,100 @@
+/* vi: set sw=4 ts=4:
+ *
+ * pidof.c - Print the PIDs of all processes with the given names.
+ *
+ * Copyright 2012 Andreas Heck <aheck@gmx.de>
+ *
+ * Not in SUSv4.
+ * See http://opengroup.org/onlinepubs/9699919799/utilities/
+
+USE_PIDOF(NEWTOY(pidof, "e@d*c#b:a", TOYFLAG_USR|TOYFLAG_BIN))
+
+config PIDOF
+	bool "pidof"
+	default y
+	help
+	  usage: pidof [NAME]...
+
+	  Print the PIDs of all processes with the given names.
+*/
+
+#include "toys.h"
+
+#define TT this.pidof
+
+#define PATH_LEN 64
+#define PROC_DIR "/proc/"
+#define CMD_LINE "/cmdline"
+
+static int matched = 0;
+
+static int for_each_pid(void (*callback) (const char *pid)) {
+    DIR *dp;
+    struct dirent *entry;
+    FILE *fp;
+    int n, pathpos;
+    char cmd[PATH_MAX];
+    char path[PATH_LEN];
+    char **curname;
+
+    dp = opendir(PROC_DIR);
+    if (!dp) {
+        perror("opendir");
+        return 1;
+    }
+
+    while ((entry = readdir(dp))) {
+        if (!isdigit(entry->d_name[0])) continue;
+        strcpy(path, PROC_DIR);
+        pathpos = strlen(PROC_DIR);
+
+        if (pathpos + strlen(entry->d_name) + 1 > PATH_LEN) continue;
+
+        strcpy(&path[pathpos], entry->d_name);
+        pathpos += strlen(entry->d_name);
+
+        if (pathpos + strlen(CMD_LINE) + 1 > PATH_LEN) continue;
+        strcpy(&path[pathpos], CMD_LINE);
+
+        fp = fopen(path, "r");
+        if (!fp) {
+            perror("fopen");
+            continue;
+        }
+
+        n = fread(cmd, 1, PATH_MAX, fp); 
+        fclose(fp);
+        if (n == 0) continue;
+
+        for (curname = toys.optargs; *curname; curname++) {
+            if (strcmp(basename(cmd), *curname) == 0) {
+                callback(entry->d_name);
+            }
+        }
+    }
+
+    closedir(dp);
+
+    return 0;
+}
+
+static void print_pid (const char *pid) {
+    if (matched) putchar(' ');
+    fputs(pid, stdout);
+    matched = 1;
+}
+
+void pidof_main(void)
+{
+    int err;
+
+    if (!toys.optargs) exit(1);
+
+    err = for_each_pid(print_pid);
+    if (err) exit(1);
+
+    if (!matched)
+        exit(1);
+    else
+        putchar('\n');
+}