AT(1) Linux ProgrammerтАЩs Manual AT(1)
at, batch, atq, atrm - queue, examine or delete jobs for later execu-
aatt [--VV] [--qq _q_u_e_u_e] [--ff _f_i_l_e] [--mmllddbbvv] TTIIMMEE
aatt [--VV] [--qq _q_u_e_u_e] [--ff _f_i_l_e] [--mmllddbbvv] -t _t_i_m_e___a_r_g
aatt --cc _j_o_b [_j_o_b_._._.]
aattqq [--VV] [--qq _q_u_e_u_e]
aattrrmm [--VV] _j_o_b [_j_o_b_._._.]
bbaattcchh [--VV] [--qq _q_u_e_u_e] [--ff _f_i_l_e] [--mmvv] [TTIIMMEE]
aatt and bbaattcchh read commands from standard input or a specified file
which are to be executed at a later time .
aatt executes commands at a specified time.
aattqq lists the userтАЩs pending jobs, unless the user is the supe-
ruser; in that case, everybodyтАЩs jobs are listed. The format
of the output lines (one for each job) is: Job number, date,
hour, job class.
aattrrmm deletes jobs, identified by their job number.
bbaattcchh executes commands when system load levels permit; in other
words, when the load average drops below 0.8, or the value
specified in the invocation of aattrruunn.
AAtt allows fairly complex time specifications, extending the POSIX.2
standard. It accepts times of the form HHHH::MMMM to run a job at a spe-
cific time of day. (If that time is already past, the next day is
assumed.) You may also specify mmiiddnniigghhtt,, nnoooonn,, or tteeaattiimmee (4pm) and
you can have a time-of-day suffixed with AAMM or PPMM for running in the
morning or the evening. You can also say what day the job will be run,
by giving a date in the form mmoonntthh--nnaammee ddaayy with an optional yyeeaarr,, or
giving a date of the form MMMMDDDDYYYY or MMMM//DDDD//YYYY or DDDD..MMMM..YYYY.. The specifi-
cation of a date _m_u_s_t follow the specification of the time of day. You
can also give times like nnooww ++ _c_o_u_n_t _t_i_m_e_-_u_n_i_t_s_, where the time-units
can be mmiinnuutteess,, hhoouurrss,, ddaayyss,, or wweeeekkss and you can tell aatt to run the
job today by suffixing the time with ttooddaayy and to run the job tomorrow
by suffixing the time with ttoommoorrrrooww..
For example, to run a job at 4pm three days from now, you would do aatt
44ppmm ++ 33 ddaayyss,, to run a job at 10:00am on July 31, you would do aatt 1100aamm
JJuull 3311 and to run a job at 1am tomorrow, you would do aatt 11aamm ttoommoorrrrooww..
The exact definition of the time specification can be found in
For both aatt and bbaattcchh, commands are read from standard input or the
file specified with the --ff option and executed. The working directory,
the environment (except for the variables TTEERRMM, DDIISSPPLLAAYY and __) and the
umask are retained from the time of invocation. An aatt - or bbaattcchh -
command invoked from a ssuu((11)) shell will retain the current userid. The
user will be mailed standard error and standard output from his com-
mands, if any. Mail will be sent using the command //uussrr//ssbbiinn//sseennddmmaaiill.
If aatt is executed from a ssuu((11)) shell, the owner of the login shell will
receive the mail.
The superuser may use these commands in any case. For other users,
permission to use at is determined by the files _/_e_t_c_/_a_t_._a_l_l_o_w and
If the file _/_e_t_c_/_a_t_._a_l_l_o_w exists, only usernames mentioned in it are
allowed to use aatt.
If _/_e_t_c_/_a_t_._a_l_l_o_w does not exist, _/_e_t_c_/_a_t_._d_e_n_y is checked, every user-
name not mentioned in it is then allowed to use aatt.
If neither exists, only the superuser is allowed use of at.
An empty _/_e_t_c_/_a_t_._d_e_n_y means that every user is allowed use these com-
mands, this is the default configuration.
--VV prints the version number to standard error.
uses the specified queue. A queue designation consists of a
single letter; valid queue designations range from aa to zz. and
AA to ZZ. The aa queue is the default for aatt and the bb queue for
bbaattcchh. Queues with higher letters run with increased niceness.
The special queue "=" is reserved for jobs which are currently
If a job is submitted to a queue designated with an uppercase letter,
it is treated as if it had been submitted to batch at that time. If
aattqq is given a specific queue, it will only show jobs pending in that
--mm Send mail to the user when the job has completed even if there
was no output.
--ff _f_i_l_e Reads the job from ffiillee rather than standard input.
--ll Is an alias for aattqq..
--dd Is an alias for aattrrmm..
--vv Shows the time the job will be executed.
Times displayed will be in the format "1997-02-20 14:50" unless
the environment variable PPOOSSIIXXLLYY__CCOORRRREECCTT is set; then, it will
be "Thu Feb 20 14:50:00 1997".
--cc cats the jobs listed on the command line to standard out-
Submit the job to be run at the time specified by the
ttiimmee__aarrgg option argument, which must have the same format
as specified for the ttoouucchh((11)) utilityтАЩs --tt time option
SSHHEELLLL The value of the SHELL environment variable at the time
of aatt invocation will determine which shell is used to
execute the aatt job commands. If SHELL is unset when aatt
is invoked, the userтАЩs login shell will be used; other-
wise, if SHELL is set when aatt is invoked, it must con-
tain the path of a shell interpreter executable that
will be used to run the commands at the specified time.
aatt will record the values of environment variables present at
time of aatt invocation. When the commands are run at the speci-
fied time, aatt will restore these variables to their recorded
values . These variables are excluded from this processing and
are never set by aatt when the commands are run :
TTEERRMM,, DDIISSPPLLAAYY,, SSHHEELLLLOOPPTTSS,, __,, PPPPIIDD,, BBAASSHH__VVEERRSSIINNFFOO,, EEUUIIDD,, UUIIDD,,
If the user submitting the aatt job is not the super-user, vari-
ables that alter the behaviour of the loader lldd..ssoo((88)),, such as
LLDD__LLIIBBRRAARRYY__PPAATTHH , cannot be recorded and restored by aatt ..
ccrroonn(1), nniiccee(1), sshh(1), uummaasskk(2), aattdd(8).
The correct operation of bbaattcchh for Linux depends on the presence
of a _p_r_o_c- type directory mounted on _/_p_r_o_c.
If the file _/_v_a_r_/_r_u_n_/_u_t_m_p is not available or corrupted, or if
the user is not logged on at the time aatt is invoked, the mail is
sent to the userid found in the environment variable LLOOGGNNAAMMEE.
If that is undefined or empty, the current userid is assumed.
AAtt and bbaattcchh as presently implemented are not suitable when
users are competing for resources. If this is the case for your
site, you might want to consider another batch system, such as
At was mostly written by Thomas Koenig, firstname.lastname@example.org-
local Nov 1996 AT(1)