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TLDR: at (tldr-pages)

Execute commands once at a later time.

  • Create commands interactively and execute them in 5 minutes (press `<Ctrl d>` when done)
    at now + 5 minutes
  • Create commands interactively and execute them at a specific time
    at {{hh:mm}}
  • Execute a command from `stdin` at 10:00 AM today
    echo "{{command}}" | at 1000
  • Execute commands from a given file next Tuesday
    at -f {{path/to/file}} 9:30 PM Tue
  • List all queued jobs for the current user (same as `atq`)
    at -l
  • View a specied job
    at -c {{job_number}}
at
NAME SYNOPSIS DESCRIPTION OPTIONS FILES SEE ALSO BUGS AUTHOR
AT(1)                                  General Commands Manual                                 AT(1)



NAME
       at, batch, atq, atrm - queue, examine, or delete jobs for later execution

SYNOPSIS
       at [-V] [-q queue] [-f file] [-u username] [-mMlv] timespec ...
       at [-V] [-q queue] [-f file] [-u username] [-mMkv] [-t time]
       at -c job [...]
       at [-V] -l [-o timeformat] [job ...]
       atq [-V] [-q queue] [-o timeformat] [job ...]
       at [-rd] job [...]
       atrm [-V] job [...]
       batch
       at -b

DESCRIPTION
       at  and  batch read commands from standard input or a specified file which are to be executed
       at a later time, using /bin/sh.

       at      executes commands at a specified time.

       atq     lists the user's pending jobs, unless the user is the superuser; in that case, every‐
               body's  jobs  are  listed.  The format of the output lines (one for each job) is: Job
               number, date, hour, queue, and username.

       atrm    deletes jobs, identified by their job number.

       batch   executes commands when system load levels permit; in other words, when the load aver‐
               age drops below 1.5, or the value specified in the invocation of atd.

       At  allows  fairly  complex  time specifications, extending the POSIX.2 standard.  It accepts
       times of the form HH:MM to run a job at a specific time of day.  (If  that  time  is  already
       past,  the  next  day is assumed.)  You may also specify midnight, noon, or teatime (4pm) and
       you can have a time-of-day suffixed with AM or PM 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 month-name day
       with an optional year, or giving a date of the form MMDD[CC]YY, MM/DD/[CC]YY, DD.MM.[CC]YY or
       [CC]YY-MM-DD.   The specification of a date must follow the specification of the time of day.
       You can also give times like now + count time-units, where the  time-units  can  be  minutes,
       hours, days, or weeks and you can tell at to run the job today by suffixing the time with to‐‐
       day and to run the job tomorrow by suffixing the time with tomorrow.

       For example, to run a job at 4pm three days from now, you would do at 4pm + 3 days, to run  a
       job  at 10:00am on July 31, you would do at 10am Jul 31 and to run a job at 1am tomorrow, you
       would do at 1am tomorrow.

       If you specify a job to absolutely run at a specific time and date in the past, the job  will
       run  as  soon  as possible.  For example, if it is 8pm and you do a at 6pm today, it will run
       more likely at 8:05pm.

       The definition of the time specification can be found in /usr/share/doc/at/timespec.

       For both at and batch, commands are read from standard input or the file specified  with  the
       -f  option  and  executed.   The working directory, the environment (except for the variables
       BASH_VERSINFO, DISPLAY, EUID, GROUPS, SHELLOPTS, TERM, UID, and _) and the umask are retained
       from the time of invocation.

       As at is currently implemented as a setuid program, other environment variables (e.g., LD_LI‐‐
       BRARY_PATH or LD_PRELOAD) are also not exported.  This may change in the future.  As a  work‐
       around, set these variables explicitly in your job.

       An  at  -  or batch - command invoked from a su(1) shell will retain the current userid.  The
       user will be mailed standard error and standard output from his commands, if any.  Mail  will
       be  sent  using  the  command  /usr/sbin/sendmail.  If at is executed from a su(1) 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 /etc/at.allow and /etc/at.deny.  See at.allow(5) for details.

OPTIONS
       -V      prints the version number to standard error and exit successfully.

       -q queue
               uses  the  specified  queue.   A queue designation consists of a single letter; valid
               queue designations range from a to z and A to Z.  The a queue is the default  for  at
               and  the  b queue for batch.  Queues with higher letters run with increased niceness.
               The special queue "=" is reserved for jobs which are currently running.

       If a job is submitted to a queue designated with an uppercase letter, the job is  treated  as
       if  it  were  submitted to batch at the time of the job.  Once the time is reached, the batch
       processing rules with respect to load average apply.  If atq is given a  specific  queue,  it
       will only show jobs pending in that queue.

       -m      Send mail to the user when the job has completed even if there was no output.

       -M      Never send mail to the user.

       -u username
               Sends mail to username rather than the current user.

       -f file Reads the job from file rather than standard input.

       -t time run the job at time, given in the format [[CC]YY]MMDDhhmm[.ss]

       -l      Is an alias for atq.

       -r      Is an alias for atrm.

       -d      Is an alias for atrm.

       -b      is an alias for batch.

       -v      Shows the time the job will be executed before reading the job.

       Times displayed will be in the format "Thu Feb 20 14:50:00 1997".

       -c     cats the jobs listed on the command line to standard output.

       -o fmt  strftime-like time format used for the job list

FILES
       /var/spool/cron/atjobs
       /var/spool/cron/atspool
       /proc/loadavg
       /var/run/utmp
       /etc/at.allow
       /etc/at.deny

SEE ALSO
       at.allow(5), at.deny(5), atd(8), cron(1), nice(1), sh(1), umask(2).

BUGS
       The  correct  operation  of batch for Linux depends on the presence of a proc- type directory
       mounted on /proc.

       If the file /var/run/utmp is not available or corrupted, or if the user is not logged  on  at
       the time at is invoked, the mail is sent to the userid found in the environment variable LOG‐‐
       NAME.  If that is undefined or empty, the current userid is assumed.

       At and batch as presently implemented are not suitable  when  users  are  competing  for  re‐
       sources.  If this is the case for your site, you might want to consider another batch system,
       such as nqs.

AUTHOR
       At was mostly written by Thomas Koenig.



                                             2009-11-14                                        AT(1)

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