.TH AT 1
.UC
.SH NAME
at \- execute commands at a later time
.SH SYNTAX
.B at
[ \-m ] 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 \fIsh\fP\|(1) or \fIcsh\fP\|(1) 
at a specified later time.
A csh script must have a '\fB#\fP' as
the first character.
If no file is given input is taken from the standard input and the
shell is determined by the SHELL environment variable.
A \fIcd\fP\|(1)
command to the current directory is inserted
at the beginning,
followed by assignments to all environment variables except TERMCAP.
In \fIcsh\fP, the
users .cshrc file is then run.  
When the script is run, it uses the user and group ID
of the creator of the copy file.
Mail is sent to that user stating
when the file ran and giving any output on stdout or stdin.
The \fB\-m\fP
flag causes no mail to be sent.
.PP
The
.I time
is 1 to 4 digits, with an optional following
`A', `P', `N' or `M' for
AM, PM, noon or midnight.  The letters may be upper or lower case.  
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.
If no day is specified, today is assumed if the time is 
after the current time.
If the time is before the current
time, tomorrow is assumed.
Names of months and days may be recognizably truncated.
Examples of legitimate commands are:
.IP
\fBat 8am jan 24
.br
at 1530 fr week\fP
.PP
.I At
scripts are executed by periodic execution
of the command
.I /usr/lib/atrun
from \fIcron\fP\|(8) typically every 5 minutes.
.SH FILES
.ns
.TP "\w'/usr/lib/atrun\ \ 'u"
/usr/spool/at/yy.ddd.hhhh.uu
activity to be performed at hour
.I hhhh
of year day
.I ddd
of year
.IR yy .
.I uu
is a unique number.
.ns
.TP
/usr/spool/at/lasttimedone
contains \fIhhhh\fP for last hour of atrun executed.
.ns
.TP
/usr/spool/at/past
directory of activities now in progress
.ns
.TP
/usr/lib/atrun
program that executes activities that
are due
.ns
.TP
\fIpwd\fP\|(1)
To find current directory
.TP
.IR Mail (1)
To mail output of script
.SH "SEE ALSO"
calendar(1),
cron(8)
.SH DIAGNOSTICS
Complains about various syntax errors and times out of range.
.br
If the process dies during execution look in \fI/usr/spool/at/past\fP for
the executing file.  The mail file is the same name as the executing file
except the first number has been changed to 'M'.
.SH BUGS
Scripts beginning with a '#' are assumed to be csh scripts;
this may be inappropriate for scripts that start with "#!/bin/sh".
.SH AUTHOR
UNIX Version 7.  Modified for \fBcsh\fP and \fBmail\fP by Peter L. Ward,
U.S. Geological Survey, Menlo Park, California.