8605 zfs channel programs: zfs.exists undocumented and non-working

illumos/illumos-gate@5f39f884e2035d671ec02148fc4d8420c670bcb4
https://github.com/illumos/illumos-gate/commit/5f39f884e2035d671ec02148fc4d8420c670bcb4

https://www.illumos.org/issues/8605
  zfs.exists() in channel programs doesn't return any result, and should have a
  man page entry.

Reviewed by: Paul Dagnelie <pcd@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: Chris Williamson <chris.williamson@delphix.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/man/man1m/zfs-program.1m b/man/man1m/zfs-program.1m
index 0834607f94e1..0e1793e9d539 100644
--- a/man/man1m/zfs-program.1m
+++ b/man/man1m/zfs-program.1m
@@ -289,6 +289,18 @@ msg (string)
 .Bd -ragged -compact -offset "xxxx"
 Debug message to be printed.
 .Ed
+.It Em zfs.exists(dataset)
+Returns true if the given dataset exists, or false if it doesn't.
+A fatal error will be thrown if the dataset is not in the target pool.
+That is, in a channel program running on rpool,
+zfs.exists("rpool/nonexistent_fs") returns false, but
+zfs.exists("somepool/fs_that_may_exist") will error.
+.Pp
+dataset (string)
+.Bd -ragged -compact -offset "xxxx"
+Dataset to check for existence.
+Must be in the target pool.
+.Ed
 .It Em zfs.get_prop(dataset, property)
 Returns two values.
 First, a string, number or table containing the property value for the given