ZFS snapshot alias

For consistency, and because it's handy, add the 'zfs snap' alias which
was introduced by Oracle Solaris 11.  This includes an update to the
man page to reflect all the available alias (snap, umount, and recv).

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #640

cmd/zfs/zfs_main.c

@@ -254,7 +254,7 @@ get_usage(zfs_help_t idx)
 	case HELP_SHARE:
 		return (gettext("\tshare <-a | filesystem>\n"));
 	case HELP_SNAPSHOT:
-		return (gettext("\tsnapshot [-r] [-o property=value] ... "
+		return (gettext("\tsnapshot|snap [-r] [-o property=value] ... "
 		    "<filesystem@snapname|volume@snapname>\n"));
 	case HELP_UNMOUNT:
 		return (gettext("\tunmount [-f] "
@@ -6161,6 +6161,12 @@ main(int argc, char **argv)
 	if (strcmp(cmdname, "recv") == 0)
 		cmdname = "receive";
 
+	/*
+	 * The 'snap' command is an alias for 'snapshot'
+	 */
+	if (strcmp(cmdname, "snap") == 0)
+		cmdname = "snapshot";
+
 	/*
 	 * Special case '-?'
 	 */

man/man8/zfs.8

@@ -37,7 +37,7 @@ zfs \- configures ZFS file systems
 
 .LP
 .nf
-\fBzfs\fR \fBsnapshot\fR [\fB-r\fR] [\fB-o\fR \fIproperty\fR=\fIvalue\fR]... 
+\fBzfs\fR \fBsnapshot | snap\fR [\fB-r\fR] [\fB-o\fR \fIproperty\fR=\fIvalue\fR]... 
       \fIfilesystem@snapname\fR|\fIvolume@snapname\fR
 .fi
 
@@ -128,7 +128,7 @@ zfs \- configures ZFS file systems
 
 .LP
 .nf
-\fBzfs\fR \fBunmount\fR [\fB-f\fR] \fB-a\fR | \fIfilesystem\fR|\fImountpoint\fR
+\fBzfs\fR \fBunmount | umount\fR [\fB-f\fR] \fB-a\fR | \fIfilesystem\fR|\fImountpoint\fR
 .fi
 
 .LP
@@ -148,12 +148,12 @@ zfs \- configures ZFS file systems
 
 .LP
 .nf
-\fBzfs\fR \fBreceive\fR [\fB-vnFu\fR] \fIfilesystem\fR|\fIvolume\fR|\fIsnapshot\fR
+\fBzfs\fR \fBreceive | recv\fR [\fB-vnFu\fR] \fIfilesystem\fR|\fIvolume\fR|\fIsnapshot\fR
 .fi
 
 .LP
 .nf
-\fBzfs\fR \fBreceive\fR [\fB-vnFu\fR] \fB-d\fR \fIfilesystem\fR
+\fBzfs\fR \fBreceive | recv\fR [\fB-vnFu\fR] \fB-d\fR \fIfilesystem\fR
 .fi
 
 .LP