# update-leap User's Manual

This document describes the use of the NTP Project's `update-leap` program.

This document applies to version 4.2.8p11 of `update-leap`.

## Short Contents

### 0.1 Invoking update-leap

`update-leap` will validate the file currently on the local system and if necessary, updates leap-second definition file.

Ordinarily, the file is found using the "leapfile" directive in `ntp.conf(5)`. However, an alternate location can be specified on the command line.

If the file does not exist, is not valid, has expired, or is expiring soon, a new copy will be downloaded. If the new copy validates, it is installed and NTP is (optionally) restarted.

If the current file is acceptable, no download or restart occurs.

-c can also be used to invoke another script to perform administrative functions, e.g. to copy the file to other local systems. .PP This can be run as a cron job. As the file is rarely updated, and leap seconds are announced at least one month in advance (usually longer), it need not be run more frequently than about once every three weeks. .PP For cron-friendly behavior, define CRONJOB=1 in the crontab. .PP This script depends on$REQUIREDCMDS

This section was generated by AutoGen, using the `agtexi-cmd` template and the option descriptions for the `update-leap` program.

#### 0.1.1 update-leap help/usage (--help)

This is the automatically generated usage text for update-leap.

The text printed is the same whether selected with the `help` option (--help) or the `more-help` option (--more-help). `more-help` will print the usage text by passing it through a pager program. `more-help` is disabled on platforms without a working `fork(2)` function. The `PAGER` environment variable is used to select the program, defaulting to more. Both will exit with a status code of 0.

#### 0.1.2 source-url option (-s)

This is the “the url of the master copy of the leapseconds file” option. This option takes a string argument. Specify the URL of the master copy to download $LEAPSRC

#### 0.1.3 ipv4 option (-4)

This is the “use only ipv4 addresses for dns name resolution” option.

This option has some usage constraints. It:

- must not appear in combination with any of the following options: ipv6.

Force DNS resolution of following host names on the command line to the IPv4 namespace. _EndOfDoc_; ;

flag = name = ipv6; flags-cant = ipv4, prefer; value = 6; descrip = "Use only IPv6 addresses for DNS name resolution"; doc = <<- _EndOfDoc_ Force DNS resolution of following host names on the command line to the IPv6 namespace. _EndOfDoc_; ;

flag = name = prefer; flags-cant = ipv4, ipv6; value = p; arg-type = keyword; keyword = 4, 6; descrip = 'Prefer IPv4 or IPv6 (as specified) addresses, but use either'; doc = <<- _EndOfDoc_ Prefer IPv4 or IPv6 (as specified) addresses, but use either.

#### 0.1.4 destination option (-d)

This is the “filename on the local system” option. This option takes a string argument float. The name to use to store the leapfile on the local system. $LEAPFILE

#### 0.1.5 expiration option (-e)

This is the “refresh the leapfile this long before it expires” option. This option takes a string argument. Specify how long before expiration the file is to be refreshed Units are required, e.g. "-e 60 days" Note that larger values imply more frequent refreshes. "$PREFETCH"

#### 0.1.6 ntp-conf-file option (-f)

This is the “location of the ntp.conf file” option. This option takes a string argument. Specify location of ntp.conf (used to make sure leapfile directive is present and to default leapfile) /etc/ntp.conf

#### 0.1.7 force-update option (-F)

This is the “force update of the leapfile” option. Force update even if current file is OK and not close to expiring.

#### 0.1.8 update-leap exit status

One of the following exit values will be returned:

0 (EXIT_SUCCESS)
  Successful program execution.
1 (EXIT_FAILURE)
  The operation failed or the command syntax was not valid.

#### 0.1.9 update-leap Usage

#### 0.1.10 update-leap Authors