выполнять команды позже (execute commands at a later time)
Описание (Description)
The at utility shall read commands from standard input and group
them together as an at-job, to be executed at a later time.
The at-job shall be executed in a separate invocation of the
shell, running in a separate process group with no controlling
terminal, except that the environment variables, current working
directory, file creation mask, and other implementation-defined
execution-time attributes in effect when the at utility is
executed shall be retained and used when the at-job is executed.
When the at-job is submitted, the at_job_id and scheduled time
shall be written to standard error. The at_job_id is an
identifier that shall be a string consisting solely of
alphanumeric characters and the <period> character. The at_job_id
shall be assigned by the system when the job is scheduled such
that it uniquely identifies a particular job.
User notification and the processing of the job's standard output
and standard error are described under the -m option.
Users shall be permitted to use at if their name appears in the
file at.allow which is located in an implementation-defined
directory. If that file does not exist, the file at.deny, which
is located in an implementation-defined directory, shall be
checked to determine whether the user shall be denied access to
at. If neither file exists, only a process with appropriate
privileges shall be allowed to submit a job. If only at.deny
exists and is empty, global usage shall be permitted. The
at.allow and at.deny files shall consist of one user name per
line.
