at.1

来自「unix v7是最后一个广泛发布的研究型UNIX版本」· 1 代码 · 共 97 行

.TH AT 1 
.SH NAME
at \- execute commands at a later time
.SH SYNOPSIS
.B at
time
[
day
]
[
file
]
.SH DESCRIPTION
.I At
squirrels away a copy of the named
.I file
(standard input default)
to be used as input to
.IR sh (1)
at a specified later time.
A
.IR cd (1)
command to the current directory is inserted
at the beginning,
followed by assignments to all environment variables.
When the script is run, it uses the user and group ID
of the creator of the copy file.
.PP
The
.I time
is 1 to 4 digits, with an optional following
`A', `P', `N' or `M' for
AM, PM, noon or midnight.
One and two digit numbers are taken to be hours, three and four digits
to be hours and minutes.
If no letters follow the digits, a 24 hour clock time is understood.
.PP
The optional
.I day
is either
(1) a month name followed by a day number,
or
(2) a day of the week; if the word `week' follows
invocation is moved seven days further off.
Names of months and days may be recognizably truncated.
Examples of legitimate commands are
.IP
at 8am jan 24
.br
at 1530 fr week
.PP
.I At
programs are executed by periodic execution
of the command
.I /usr/lib/atrun
from
.IR cron (8).
The granularity of
.I at
depends upon how often
.I atrun
is executed.
.PP
Standard output or error output is lost unless redirected.
.SH FILES
/usr/spool/at/yy.ddd.hhhh.uu
.br
activity to be performed at hour
.I hhhh
of year day
.I ddd
of year
.IR yy .
.I uu
is a unique number.
.br
/usr/spool/at/lasttimedone contains
.I hhhh
for last hour of activity.
.br
/usr/spool/at/past directory of activities now in progress
.br
/usr/lib/atrun program that executes activities that
are due
.br
pwd(1)
.SH "SEE ALSO"
calendar(1),
cron(8)
.SH DIAGNOSTICS
Complains about various syntax errors and times out of range.
.SH BUGS
Due to the granularity of the execution of
.I /usr/lib/atrun,
there may be bugs in scheduling things almost
exactly 24 hours into the future.