diff --git a/plugins/sudoers/Makefile.in b/plugins/sudoers/Makefile.in
index 4c89af187..b19f1d5f7 100644
--- a/plugins/sudoers/Makefile.in
+++ b/plugins/sudoers/Makefile.in
@@ -103,8 +103,9 @@ LIBSUDOERS_OBJS = alias.lo audit.lo defaults.lo gram.lo match.lo pwutil.lo \
 		  timestr.lo toke.lo redblack.lo
 
 SUDOERS_OBJS = $(AUTH_OBJS) boottime.lo check.lo env.lo goodpath.lo \
-	       group_plugin.lo find_path.lo interfaces.lo logging.lo parse.lo \
-	       set_perms.lo sudoers.lo sudo_nss.lo iolog.lo @SUDOERS_OBJS@
+	       group_plugin.lo find_path.lo interfaces.lo logging.lo \
+	       parse.lo set_perms.lo sudoers.lo sudo_nss.lo iolog.lo \
+	       iolog_path.lo @SUDOERS_OBJS@
 
 VISUDO_OBJS = visudo.o goodpath.o find_path.o error.o
 
@@ -221,6 +222,8 @@ interfaces.lo: $(srcdir)/interfaces.c $(SUDODEP) $(srcdir)/interfaces.h
 	$(LIBTOOL) --mode=compile $(CC) -c $(CPPFLAGS) $(CFLAGS) $(DEFS) $(srcdir)/interfaces.c
 iolog.lo: $(srcdir)/iolog.c $(SUDODEP)
 	$(LIBTOOL) --mode=compile $(CC) -c $(CPPFLAGS) $(CFLAGS) $(DEFS) $(srcdir)/iolog.c
+iolog_path.lo: $(srcdir)/iolog_path.c $(SUDODEP)
+	$(LIBTOOL) --mode=compile $(CC) -c $(CPPFLAGS) $(CFLAGS) $(DEFS) $(srcdir)/iolog_path.c
 ldap.lo: $(srcdir)/ldap.c $(SUDODEP) $(srcdir)/parse.h $(incdir)/list.h
 	$(LIBTOOL) --mode=compile $(CC) -c $(CPPFLAGS) $(CFLAGS) $(DEFS) $(srcdir)/ldap.c
 linux_audit.lo: $(srcdir)/linux_audit.c $(SUDODEP) $(srcdir)/linux_audit.h
diff --git a/plugins/sudoers/def_data.c b/plugins/sudoers/def_data.c
index b440c54c1..5be92807b 100644
--- a/plugins/sudoers/def_data.c
+++ b/plugins/sudoers/def_data.c
@@ -334,6 +334,10 @@ struct sudo_defs_types sudo_defs_table[] = {
 	"iolog_dir", T_STR|T_PATH,
 	"Directory in which to store input/output logs",
 	NULL,
+    }, {
+	"iolog_file", T_STR,
+	"File in which to store the input/output log",
+	NULL,
     }, {
 	NULL, 0, NULL
     }
diff --git a/plugins/sudoers/def_data.h b/plugins/sudoers/def_data.h
index cb2b9ac3c..b510b21db 100644
--- a/plugins/sudoers/def_data.h
+++ b/plugins/sudoers/def_data.h
@@ -154,6 +154,8 @@
 #define I_GROUP_PLUGIN          76
 #define def_iolog_dir           (sudo_defs_table[77].sd_un.str)
 #define I_IOLOG_DIR             77
+#define def_iolog_file          (sudo_defs_table[78].sd_un.str)
+#define I_IOLOG_FILE            78
 
 enum def_tupple {
 	never,
diff --git a/plugins/sudoers/def_data.in b/plugins/sudoers/def_data.in
index d19579053..655b3470d 100644
--- a/plugins/sudoers/def_data.in
+++ b/plugins/sudoers/def_data.in
@@ -247,3 +247,6 @@ group_plugin
 iolog_dir
 	T_STR|T_PATH
 	"Directory in which to store input/output logs"
+iolog_file
+	T_STR
+	"File in which to store the input/output log"
diff --git a/plugins/sudoers/defaults.c b/plugins/sudoers/defaults.c
index 60c1104b9..4d64c9bc0 100644
--- a/plugins/sudoers/defaults.c
+++ b/plugins/sudoers/defaults.c
@@ -443,7 +443,8 @@ init_defaults(void)
 #ifdef UMASK_OVERRIDE
     def_umask_override = TRUE;
 #endif
-    def_iolog_dir = _PATH_SUDO_IO_LOGDIR;
+    def_iolog_file = estrdup("%{seq}");
+    def_iolog_dir = estrdup(_PATH_SUDO_IO_LOGDIR);
     def_sudoers_locale = estrdup("C");
     def_env_reset = TRUE;
     def_set_logname = TRUE;
diff --git a/plugins/sudoers/iolog.c b/plugins/sudoers/iolog.c
index 554fef9fa..7ba618bb6 100644
--- a/plugins/sudoers/iolog.c
+++ b/plugins/sudoers/iolog.c
@@ -84,6 +84,26 @@ static struct timeval last_time;
 static union io_fd io_fds[IOFD_MAX];
 extern struct io_plugin sudoers_io;
 
+static void
+mkdir_parents(char *path)
+{
+    struct stat sb;
+    char *slash = path;
+
+    for (;;) {
+	if ((slash = strchr(slash + 1, '/')) == NULL)
+	    break;
+	*slash = '\0';
+	if (stat(path, &sb) != 0) {
+	    if (mkdir(path, S_IRWXU) != 0)
+		log_error(USE_ERRNO, "Can't mkdir %s", path);
+	} else if (!S_ISDIR(sb.st_mode)) {
+	    log_error(0, "%s: %s", path, strerror(ENOTDIR));
+	}
+	*slash = '/';
+    }
+}
+
 void
 io_nextid(void)
 {
@@ -98,6 +118,7 @@ io_nextid(void)
     /*
      * Create I/O log directory if it doesn't already exist.
      */
+    mkdir_parents(def_iolog_dir);
     if (stat(def_iolog_dir, &sb) != 0) {
 	if (mkdir(def_iolog_dir, S_IRWXU) != 0)
 	    log_error(USE_ERRNO, "Can't mkdir %s", def_iolog_dir);
@@ -152,72 +173,36 @@ io_nextid(void)
 }
 
 static int
-build_idpath(const char *iolog_dir, const char *sessid, char *pathbuf, size_t pathsize)
+build_iopath(const char *iolog_dir, const char *iolog_file, char *pathbuf,
+    size_t pathsize)
 {
-    struct stat sb;
-    char *cp;
-    int i, len;
+    int dirlen, filelen, len;
 
-    if (sessid[0] == '\0')
-	log_error(0, "tried to build a session id path without a session id");
+    /* Trim extraneous slashes. */
+    dirlen = strlen(iolog_dir);
+    while (dirlen > 1 && iolog_dir[dirlen - 1] == '/')
+	dirlen--;
+    while (*iolog_file == '/')
+	iolog_file++;
+    filelen = strlen(iolog_file);
+    while (filelen > 1 && iolog_file[filelen - 1] == '/')
+	filelen--;
 
-    /* Check whether or not we have a real session ID. */
-    for (i = 0; i < 6; i++) {
-	switch (sessid[i]) {
-	    case '0': case '1': case '2': case '3': case '4': case '5':
-	    case '6': case '7': case '8': case '9': case 'A': case 'B':
-	    case 'C': case 'D': case 'E': case 'F': case 'G': case 'H':
-	    case 'I': case 'J': case 'K': case 'L': case 'M': case 'N':
-	    case 'O': case 'P': case 'Q': case 'R': case 'S': case 'T':
-	    case 'U': case 'V': case 'W': case 'X': case 'Y': case 'Z':
-		break;
-	    default:
-		goto checked;
-	}
+    if (*iolog_dir != '/' || *iolog_file == '\0')
+	log_error(0, "invalid I/O log path: %s/%s", iolog_dir, iolog_file);
+
+    len = snprintf(pathbuf, pathsize, "%.*s/%.*s", dirlen, iolog_dir,
+	filelen, iolog_file);
+    if (len <= 0 && len >= pathsize) {
+	errno = ENAMETOOLONG;
+	log_error(USE_ERRNO, "%.*s/%.*s", dirlen, iolog_dir,
+	    filelen, iolog_file);
     }
-checked:
-    if (i == 6 && sessid[6] == '\0') {
-	/* Path is of the form /var/log/sudo-io/00/00/01. */
-	len = snprintf(pathbuf, pathsize, "%s/%c%c/%c%c/%c%c", iolog_dir,
-	    sessid[0], sessid[1], sessid[2], sessid[3], sessid[4], sessid[5]);
-	if (len <= 0 && len >= pathsize) {
-	    errno = ENAMETOOLONG;
-	    log_error(USE_ERRNO, "%s/%s", iolog_dir, sessid);
-	}
 
-	/* Create the intermediate subdirs as needed. */
-	for (i = 6; i > 0; i -= 3) {
-	    pathbuf[len - i] = '\0';
-	    if (stat(pathbuf, &sb) != 0) {
-		if (mkdir(pathbuf, S_IRWXU) != 0)
-		    log_error(USE_ERRNO, "Can't mkdir %s", pathbuf);
-	    } else if (!S_ISDIR(sb.st_mode)) {
-		log_error(0, "%s: %s", pathbuf, strerror(ENOTDIR));
-	    }
-	    pathbuf[len - i] = '/';
-	}
-    } else {
-	/* Not a session ID, just append dir + file. */
-	len = snprintf(pathbuf, pathsize, "%s/%s", iolog_dir, sessid);
-	if (len <= 0 && len >= pathsize) {
-	    errno = ENAMETOOLONG;
-	    log_error(USE_ERRNO, "%s/%s", iolog_dir, sessid);
-	}
-
-	/* Create the intermediate subdirs as needed. */
-	cp = &pathbuf[strlen(iolog_dir)];
-	do {
-	    *cp = '\0';
-	    if (stat(pathbuf, &sb) != 0) {
-		if (mkdir(pathbuf, S_IRWXU) != 0)
-		    log_error(USE_ERRNO, "Can't mkdir %s", pathbuf);
-	    } else if (!S_ISDIR(sb.st_mode)) {
-		log_error(0, "%s: %s", pathbuf, strerror(ENOTDIR));
-	    }
-	    *cp++ = '/';
-	    cp = strchr(cp, '/');
-	} while (cp != NULL);
-    }
+    /* Create path and intermediate subdirs as needed. */
+    mkdir_parents(pathbuf);
+    if (mkdtemp(pathbuf) == NULL)
+	log_error(USE_ERRNO, "Can't create %s", pathbuf);
 
     return(len);
 }
@@ -272,8 +257,8 @@ sudoers_io_open(unsigned int version, sudo_conv_t conversation,
     /*
      * Pull iolog settings out of command_info, if any.
      */
-    iolog_dir = def_iolog_dir;
-    iolog_file = sudo_user.sessid;
+    iolog_dir = _PATH_SUDO_IO_LOGDIR; /* XXX */
+    iolog_file = sudo_user.sessid; /* XXX */
     iolog_stdin = iolog_ttyin = def_log_input;
     iolog_stdout = iolog_stderr = iolog_ttyout = def_log_output;
     for (cur = command_info; *cur != NULL; cur++) {
@@ -319,20 +304,17 @@ sudoers_io_open(unsigned int version, sudo_conv_t conversation,
 	return FALSE;
 
     /* If no I/O log file defined there is nothing to do. */
-    if (iolog_file == NULL)
+    if (iolog_file == NULL || iolog_dir == NULL)
 	return FALSE;
 
     /*
-     * Build a path containing the session ID split into two-digit subdirs,
-     * so ID 000001 becomes /var/log/sudo-io/00/00/01.
+     * Build a path from I/O file and dir, creating intermediate subdirs
+     * and calling mkdtemp() on the result.
      */
-    len = build_idpath(iolog_dir, iolog_file, pathbuf, sizeof(pathbuf));
-    if (len == -1)
+    len = build_iopath(iolog_dir, iolog_file, pathbuf, sizeof(pathbuf));
+    if (len < 0 || len >= sizeof(pathbuf))
 	return -1;
 
-    if (mkdir(pathbuf, S_IRUSR|S_IWUSR|S_IXUSR) != 0)
-	log_error(USE_ERRNO, "Can't mkdir %s", pathbuf);
-
     /*
      * We create 7 files: a log file, a timing file and 5 for input/output.
      */
diff --git a/plugins/sudoers/iolog_path.c b/plugins/sudoers/iolog_path.c
new file mode 100644
index 000000000..0ea707bc3
--- /dev/null
+++ b/plugins/sudoers/iolog_path.c
@@ -0,0 +1,229 @@
+/*
+ * Copyright (c) 2010 Todd C. Miller <Todd.Miller@courtesan.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <config.h>
+
+#include <sys/types.h>
+#include <stdio.h>
+#ifdef STDC_HEADERS
+# include <stdlib.h>
+# include <stddef.h>
+#else
+# ifdef HAVE_STDLIB_H
+#  include <stdlib.h>
+# endif
+#endif /* STDC_HEADERS */
+#ifdef HAVE_STRING_H
+# if defined(HAVE_MEMORY_H) && !defined(STDC_HEADERS)
+#  include <memory.h>
+# endif
+# include <string.h>
+#endif /* HAVE_STRING_H */
+#ifdef HAVE_STRINGS_H
+# include <strings.h>
+#endif /* HAVE_STRINGS_H */
+#ifdef HAVE_SETLOCALE
+# include <locale.h>
+#endif
+#include <pwd.h>
+#include <grp.h>
+#include <time.h>
+
+#include "sudoers.h"
+
+struct path_escape {
+    const char *name;
+    size_t (*copy_fn)(char *, size_t);
+};
+
+static size_t fill_seq(char *, size_t);
+static size_t fill_user(char *, size_t);
+static size_t fill_group(char *, size_t);
+static size_t fill_runas_user(char *, size_t);
+static size_t fill_runas_group(char *, size_t);
+static size_t fill_hostname(char *, size_t);
+static size_t fill_command(char *, size_t);
+
+static struct path_escape escapes[] = {
+    { "seq", fill_seq },
+    { "user", fill_user },
+    { "group", fill_group },
+    { "runas_user", fill_runas_user },
+    { "runas_group", fill_runas_group },
+    { "hostname", fill_hostname },
+    { "command", fill_command },
+    { NULL, NULL }
+};
+
+static size_t
+fill_seq(char *str, size_t strsize)
+{
+    int len;
+
+    /* Path is of the form /var/log/sudo-io/00/00/01. */
+    len = snprintf(str, strsize, "%c%c/%c%c/%c%c", sudo_user.sessid[0],
+	sudo_user.sessid[1], sudo_user.sessid[2], sudo_user.sessid[3],
+	sudo_user.sessid[4], sudo_user.sessid[5]);
+    if (len < 0)
+	return strsize;	/* handle non-standard snprintf() */
+    return (size_t)len;
+}
+
+static size_t
+fill_user(char *str, size_t strsize)
+{
+    return strlcpy(str, user_name, strsize);
+}
+
+static size_t
+fill_group(char *str, size_t strsize)
+{
+    struct group *grp;
+    size_t len;
+
+    if ((grp = sudo_getgrgid(user_gid)) != NULL) {
+	len = strlcpy(str, grp->gr_name, strsize);
+	gr_delref(grp);
+    } else {
+	len = strlen(str);
+	len = snprintf(str + len, strsize - len, "#%u",
+	    (unsigned int) user_gid);
+    }
+    return len;
+}
+
+static size_t
+fill_runas_user(char *str, size_t strsize)
+{
+    return strlcpy(str, runas_pw->pw_name, strsize);
+}
+
+static size_t
+fill_runas_group(char *str, size_t strsize)
+{
+    struct group *grp;
+    size_t len;
+
+    if (runas_gr != NULL) {
+	len = strlcpy(str, runas_gr->gr_name, strsize);
+    } else {
+	if ((grp = sudo_getgrgid(runas_pw->pw_gid)) != NULL) {
+	    len = strlcpy(str, grp->gr_name, strsize);
+	    gr_delref(grp);
+	} else {
+	    len = strlen(str);
+	    len = snprintf(str + len, strsize - len, "#%u",
+		(unsigned int) runas_pw->pw_gid);
+	}
+    }
+    return len;
+}
+
+static size_t
+fill_hostname(char *str, size_t strsize)
+{
+    return strlcpy(str, user_shost, strsize);
+}
+
+static size_t
+fill_command(char *str, size_t strsize)
+{
+    return strlcpy(str, user_base, strsize);
+}
+
+char *
+expand_iolog_path(const char *prefix, const char *opath)
+{
+    size_t plen = 0, psize = 1024;
+    char *path, *dst;
+    const char *src, *ep;
+    int strfit = FALSE;
+
+    /* Copy opath -> path, expanding any escape sequences. */
+    dst = path = emalloc(psize);
+    *path = '\0';
+
+    if (prefix != NULL) {
+	plen = strlcpy(path, prefix, psize);
+	dst += plen;
+    }
+    for (src = opath; *src != '\0'; src++) {
+	if (src[0] == '%') {
+	    if (src[1] == '{') {
+		ep = strchr(src + 2, '}');
+		if (ep != NULL) {
+		    struct path_escape *esc;
+		    size_t len = (size_t)(ep - src - 2);
+		    for (esc = escapes; esc->name != NULL; esc++) {
+			if (strncmp(src + 2, esc->name, len) == 0 &&
+			    esc->name[len] == '\0')
+			    break;
+		    }
+		    for (;;) {
+			len = esc->copy_fn(dst, psize - (dst - path));
+			if (len < psize - (dst - path))
+			    break;
+			path = erealloc3(path, 2, psize);
+			psize *= 2;
+			dst = path + plen;
+		    }
+		    dst += len;
+		    src = ep;
+		    continue;
+		}
+	    } else {
+		/* May need strftime() */
+		strfit = 1;
+	    }
+	}
+	/* Need at least 2 chars, including the NUL terminator. */
+	if (plen + 2 >= psize) {
+	    path = erealloc3(path, 2, psize);
+	    psize *= 2;
+	    dst = path + plen;
+	}
+	*dst++ = *src;
+    }
+    *dst = '\0';
+
+    if (strfit) {
+	time_t now;
+	struct tm *timeptr;
+	char *buf = NULL;
+
+	time(&now);
+	timeptr = localtime(&now);
+
+#ifdef HAVE_SETLOCALE
+	if (!setlocale(LC_ALL, def_sudoers_locale)) {
+	    warningx("unable to set locale to \"%s\", using \"C\"",
+		def_sudoers_locale);
+	    setlocale(LC_ALL, "C");
+	}
+#endif
+	/* Double the size of the buffer until it is big enough to expand. */
+	do {
+	    psize * 2;
+	    buf = erealloc(buf, psize);
+	    buf[psize - 1] = '\0';
+	} while (!strftime(buf, psize, path, timeptr) || buf[psize - 1] != '\0');
+	setlocale(LC_ALL, "");
+	efree(path);
+	path = buf;
+    }
+
+    return path;
+}
diff --git a/plugins/sudoers/plugin_error.c b/plugins/sudoers/plugin_error.c
index c4a6a996e..2d42871b7 100644
--- a/plugins/sudoers/plugin_error.c
+++ b/plugins/sudoers/plugin_error.c
@@ -32,7 +32,7 @@
 static void _warning(int, const char *, va_list);
        void plugin_cleanup(int);
 
-extern sigjmp_buf error_jmp;
+sigjmp_buf error_jmp;
 
 extern sudo_conv_t sudo_conv;
 
diff --git a/plugins/sudoers/sudoers.c b/plugins/sudoers/sudoers.c
index 08933fca4..021fe677e 100644
--- a/plugins/sudoers/sudoers.c
+++ b/plugins/sudoers/sudoers.c
@@ -135,8 +135,8 @@ static struct sudo_nss_list *snl;
 int NewArgc;
 char **NewArgv;
 
-/* error.c */
-sigjmp_buf error_jmp;
+/* plugin_error.c */
+extern sigjmp_buf error_jmp;
 
 static int
 sudoers_policy_open(unsigned int version, sudo_conv_t conversation,
@@ -500,9 +500,13 @@ sudoers_policy_main(int argc, char * const argv[], int pwflag, char *env_add[],
     }
 
     if (ISSET(sudo_mode, (MODE_RUN | MODE_EDIT)) && (def_log_input || def_log_output)) {
-	io_nextid();
-	command_info[info_len++] = fmt_string("iolog_dir", def_iolog_dir);
-	command_info[info_len++] = fmt_string("iolog_file", sudo_user.sessid);
+	if (def_iolog_file) {
+	    if (strstr(def_iolog_file, "%{seq}") != NULL) /* XXX - inline? */
+		io_nextid();
+	    command_info[info_len++] = expand_iolog_path("iolog_file=", def_iolog_file);
+	}
+	if (def_iolog_dir)
+	    command_info[info_len++] = expand_iolog_path("iolog_dir=", def_iolog_dir);
 	if (def_log_input) {
 	    command_info[info_len++] = estrdup("iolog_stdin=true");
 	    command_info[info_len++] = estrdup("iolog_ttyin=true");
diff --git a/plugins/sudoers/sudoers.h b/plugins/sudoers/sudoers.h
index 44826ae65..e9a125250 100644
--- a/plugins/sudoers/sudoers.h
+++ b/plugins/sudoers/sudoers.h
@@ -285,6 +285,9 @@ int get_boottime(struct timeval *);
 /* iolog.c */
 void io_nextid(void);
 
+/* iolog_path.c */
+char *expand_iolog_path(const char *prefix, const char *opath);
+
 /* env.c */
 char **env_get(void);
 void env_init(char * const envp[]);