The following environment variables shall affect the execution of
at:
LANG Provide a default value for the internationalization
variables that are unset or null. (See the Base
Definitions volume of POSIX.1‐2017, Section 8.2,
Internationalization Variables for the precedence of
internationalization variables used to determine the
values of locale categories.)
LC_ALL If set to a non-empty string value, override the values
of all the other internationalization variables.
LC_CTYPE Determine the locale for the interpretation of
sequences of bytes of text data as characters (for
example, single-byte as opposed to multi-byte
characters in arguments and input files).
LC_MESSAGES
Determine the locale that should be used to affect the
format and contents of diagnostic messages written to
standard error and informative messages written to
standard output.
NLSPATH Determine the location of message catalogs for the
processing of LC_MESSAGES.
LC_TIME Determine the format and contents for date and time
strings written and accepted by at.
SHELL Determine a name of a command interpreter to be used to
invoke the at-job. If the variable is unset or null, sh
shall be used. If it is set to a value other than a
name for sh, the implementation shall do one of the
following: use that shell; use sh; use the login shell
from the user database; or any of the preceding
accompanied by a warning diagnostic about which was
chosen.
TZ Determine the timezone. The job shall be submitted for
execution at the time specified by timespec or -t time
relative to the timezone specified by the TZ variable.
If timespec specifies a timezone, it shall override TZ.
If timespec does not specify a timezone and TZ is unset
or null, an unspecified default timezone shall be used.
