APPLYLOG(8) System Manager's Manual APPLYLOG(8)

applylog, updatelog - log-based updates

install/applylog [ -c ] [ -e ] [ -n ] [ -s ] [ -u ] [ -g ] [ -v ] [ -T timefile ] clientlog clientroot serverroot [ path ... ]

install/updatelog [ -p proto ] [ -r root ] [ -t now gen ] [ -c ] [ -x path ] log [ path ... ]

These two commands allow distribution of updates (eg, to the Inferno tree) based on a log of changes since a previous update. Notionally, one server system is the primary for a set of files, and one or more client systems maintain replicas of that set, although in some applications server and client might be the same machine.

Applylog is run on a client, to update the file tree rooted at clientroot. The server's version of the tree is rooted at serverroot on the client, typically by being mounted there (see bind (1)). Applylog takes the current state of the replica from the entries in clientlog, and applies a set of changes represented by log entries read from its standard input. Those entries are provided by the server. Each change is examined to see whether the file to which it applies is in the expected state. If so, the change is applied without comment; otherwise, there is a conflict caused by a local change to the replica tree independently from the primary. By default, applylog diagnoses the conflict and does not apply the change. It accepts the following options:

Resolve inconsistencies in favour of the client: leave the replica as is.
Exit with an error status on any error, including inconsistency between client and server.
Print on standard output a list of changes that would be made, and list any conflicts, but do not change the tree or update the log.
Resolve inconsistencies in favour of the server: make the replica match the server's state.
Make file ownership in the replica match that on the server.
Make group ownership in the replica match that on the server.
Print a summary of each log entry as it is examined.
Read a time and sequence number from timefile and apply only log entries with stamps greater than that. On successful completion, if the -n option is not given, update the timefile with the stamp of the last log entry processed successfully.

The scope of an update in a tree can be restricted to a particular set of paths listed on the command line. They should all be relative path names.

Updatelog is run on a server to produce a sequence of log entries representing changes to the primary tree since a previous log was produced. It can also be run on a client to see how its replica state differs from that recorded in a log. It accepts the following options:

Use proto as the prototype for the file system, as described by proto (6) (default: /lib/proto/all).
The replica is rooted at root (default: the current directory, .).
Make log entries use time now and initial sequence number gen. The defaults are the current time and 0.
Produce output only for content and metadata changes, not additions or deletions.
Exclude path and its subtrees from consideration.

By default, updatelog produces log entries describing changes, additions and deletions to all files in root but the scope can be limited by giving a different proto, explicitly listing trees to consider as paths on the command line, and by giving one or more -x options to exclude particular paths, in any desired combination.

A log file is a text file with one line representing each change to the tree. Each line has the form:

time gen verb path serverpath mode uid gid mtime length [ sum ... ]

where:

are decimal numbers that order the sequence of requests: time is typically the time in seconds of the epoch at which the entry was made; gen is a monotonically increasing sequence number
is an action:
add file path
change the contents of file path
delete path
change the metadata (permissions, ownership) for path
the name of the file on the client
the name of the file on the server with the contents for path, or simply when the server and client file names are the same
the resulting metadata (except for d where the metadata is that for the file to be deleted)
is the MD5 checksum of the file's contents

/appl/cmd/install/applylog.b
/appl/cmd/install/logs.b
/appl/cmd/install/updatelog.b

fs (1), kfs (4), proto (6)