man pages section 4: File Formats

synclist(4)

Name

synclist– list of files to be synchronized when changing from one boot environment to another

Synopsis

/etc/lu/synclist

Description

The synclist file lists files that will be synchronized when you switch from one boot environment (BE) to another. The file is part of the Live Upgrade feature of the Solaris Operating Environment. See live_upgrade(5) for an overview of the Live Upgrade software.

The synclist file consists of a list of entries, with two fields per entry. The first field is a pathname, the second a keyword. The keyword can be one of OVERWRITE, APPEND, or PREPEND. The meanings of these keywords is described below. synclist accepts comments; a comment is indicated by a hash mark (#) in the first character position on a line.

The way in which a file is updated is indicated by the keyword in the second field of its synclist entry. All of these operations occur upon the first boot of a newly activated BE. The keywords have the following semantics:

OVERWRITE: Overwrite the contents of a file with the contents of the file of the same name on the previously booted BE. Both directories and files can be specified for overwriting. If you specify a directory, every file in and beneath the listed directory is subject to being overwritten. (Whether an individual file or directory is overwritten depends on the outcome of the comparison of file versions, described below.) Following an overwrite operation, a file on a new BE has the same date of creation, mode, and ownership as the file of the same name on the previously booted BE.
APPEND: Append the contents of a file on the previously booted BE to the contents of the file of the same name on the new BE. Use of APPEND allows for the possibility of duplicate entries in a file. You cannot use APPEND with directories. Following an append operation, a file on a new BE will have a different modified date and time from the same file on the previously booted BE. The mode and ownership will be the same between the two files.
PREPEND: Prepend the contents of a file on the previously booted BE to the contents of the file of the same name on the new BE. Use of PREPEND allows for the possibility of duplicate entries in a file. You cannot use PREPEND with directories. Following a prepend operation, a file on a new BE will have a different modified date and time from the same file on the previously booted BE. The mode and ownership will be the same between the two files.

The second (keyword) field in a synclist entry can be empty, in which case the OVERWRITE action is assumed.

In deciding when to update a file on a newly activated BE, Live Upgrade uses an algorithm illustrated in the table below. In the table, “old” refers to a BE relinquishing activated status; “new” refers to a newly activated BE. The “resulting state” occurs when the new BE is first booted.

State of File on Old BE	State of File on New BE	Resulting State on New BE
Unchanged	Unchanged	Not updated
Updated	Unchanged	Updated
Unchanged	Updated	Not updated
Updated	Updated	Conflict Indicated

When a file is updated on both an old and new BE, as shown in the last row of the table above, Live Upgrade reports the conflict and allows you to resolve it.

Modify the contents of synclist with caution. Adding certain files to synclist might render a BE unbootable. Also, be careful in using the file-inclusion and –exclusion options in lucreate(1M) in conjunction with changes you might make in synclist. Again, you could render a system unbootable or end up with different results from what you expected.

Switching BEs among different Solaris Operating Environment marketing releases (for example, from a Solaris 9 BE to a Solaris 2.6 BE) requires care. This is especially true if you make any modifications to synclist. For example, consider that the last-active BE contains Solaris 9 and you want to activate a BE that contains Solaris 2.6. In synclist in the Solaris 9 BE, you have added files that are present in Solaris 9 that are not present in Solaris 2.6 or that are no longer compatible with Solaris 2.6. If you forced synchronization with the luactivate(1M) -s option, the BE containing Solaris 2.6 might be synchronized with files that might not work under Solaris 2.6.

Examples

Example 1 Updating the `passwd` File

Consider the following scenario:

You create a BE, named first.
You create a new BE, named second, using first as the source.
You add a new user to first, thereby making an addition to the passwd file in first.
Using luactivate(1M), you activate second. At this point, Live Upgrade recognizes that the passwd file has been updated in first and not in second.
When you boot second for the first time, Live Upgrade, directed by the keyword OVERWRITE in synclist, copies passwd from first to second, overwriting the contents in the latter BE.

The result described above obtains with any of the files associated with the OVERWRITE keyword in synclist. If the reverse had occurred—you edited passwd on second and left passwd in first untouched—Live Upgrade would not have modified passwd in second when that BE was first booted.

Example 2 Updating the `/var/log/syslog` File

Consider the following scenario:

You create a BE, named first.
You create a new BE, named second, using first as the source.
Logging occurs, adding to the contents of /var/log/syslog in first.
Using luactivate(1M), you activate second. At this point, Live Upgrade recognizes that /var/log/syslog has been updated in first and not in second.
When you boot second for the first time, Live Upgrade, directed by the keyword APPEND in synclist, appends the contents of /var/log/syslog in first to the same file in second.

The result described above obtains with any of the files associated with the APPEND keyword in synclist. If the reverse had occurred—you changed /var/log/syslog on second and left /var/log/syslog in first untouched—Live Upgrade would not have modified /var/log/syslog in second when that BE was first booted.

Attributes

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Availability	SUNWluu
Interface Stability	Evolving