Tribblix: manual page: touch.1

TOUCH(1) User Commands TOUCH(1)

NAME

touch, settime - change file access and modification times

SYNOPSIS

touch [-acm] [-r ref_file | -t time | -d date_time] file...

touch [-acm] [time_spec] file...

settime [-f ref_file] [time_spec] file...

DESCRIPTION

The touch utility sets the access and modification times of each
file. The file operand is created if it does not already exist.

The time used can be specified by -t time, by -d date_time, by the
corresponding time fields of the file referenced by -r ref_file, or
by the time_spec operand. If none of these are specified, touch uses
the current time.

If neither the -a nor -m options are specified, touch updates both
the modification and access times.

A user with write access to a file, but who is not the owner of the
file or a super-user, can change the modification and access times of
that file only to the current time. Attempts to set a specific time
with touch results in an error.

The settime utility is equivalent to touch -c [time_spec] file.

OPTIONS

The following options are supported in the touch and settime
utilities:

touch
The following options are supported for the touch utility:

-a

Changes the access time of file. Does not change the modification
time unless -m is also specified.

-c

Does not create a specified file if it does not exist. Does not
write any diagnostic messages concerning this condition.

-d date_time

Uses the specified date_time instead of the current time. The
option-argument must be a string of the form:

YYYY-MM-DDThh:mm:SS[.frac][tz]

or

YYYY-MM-DDThh:mm:SS[,frac][tz]

where

o YYYY is at least four decimal digits giving the year

o MM, DD, hh, mm, and SS are as with -t time

o T is either the letter T or a single SPACE character

o [.frac] and [,frac] are either empty, or a period (.)
or a comma (,) respectively, followed by one or more
decimal digits, specifying a fractional second

o [tz] is either empty, signifying local time, or the
letter Z, signifying UTC. If [tz] is empty, the
resulting time is affected by the value of the TZ
environment variable

-m

Changes the modification time of file. Does not change the access
time unless -a is also specified.

-r ref_file

Uses the corresponding times of the file named by ref_file
instead of the current time.

-t time

Uses the specified time instead of the current time. time is a
decimal number of the form:

[[CC]YY]MMDDhhmm[.SS]

where each two digits represent the following:

MM

The month of the year [01-12].

DD

The day of the month [01-31].

hh

The hour of the day [00-23].

mm

The minute of the hour [00-59].

CC

The first two digits of the year.

YY

The second two digits of the year.

SS

The second of the minute [00-61].

Both CC and YY are optional. If neither is given, the current
year is assumed. If YY is specified, but CC is not, CC is derived
as follows:

+------------------------+
|If YY is: CC becomes: |
+------------------------+
|69-99 19 |
|00-38 20 |
|39-68 ERROR |
+------------------------+
The resulting time is affected by the value of the TZ environment
variable. If the resulting time value precedes the Epoch, touch
exits immediately with an error status. The range of valid times
is the Epoch to January 18, 2038.

The range for SS is [00-61] rather than [00-59] because of leap
seconds. If SS is 60 or 61, and the resulting time, as affected
by the TZ environment variable, does not refer to a leap second,
the resulting time is one or two seconds after a time where SS is
59. If SS is not given, it is assumed to be 0.

settime
The following option is supported for the settime utility:

-f ref_file

Uses the corresponding times of the file named by ref_file
instead of the current time.

OPERANDS

The following operands are supported for the touch and settime
utilities:

file

A path name of a file whose times are to be modified.

time_spec

Uses the specified time_spec instead of the current time. This
operand is a decimal number of the form:

MMDDhhmm[YY]

where each two digits represent the following:

MM

The month of the year [01-12].

DD

The day of the month [01-31].

hh

The hour of the day [00-23].

mm

The minute of the hour [00-59].

YY

The second two digits of the year.

YY is optional. If it is omitted, the current year is
assumed. If YY is specified, the year is derived as follows:

+---------------------------+
| YY Corresponding Year |
|69-99 1969-1999 |
|00-38 2000-2038 |
|39-68 ERROR |
+---------------------------+
If no -d, -r, or -t option is specified, at least two operands
are specified, and the first operand is an eight- or ten-digit
decimal integer, the first operand is assumed to be a time_spec
operand. Otherwise, the first operand is assumed to be a file
operand.

USAGE

See largefile(7) for the description of the behavior of touch when
encountering files greater than or equal to 2 Gbyte ( 2^31 bytes).

ENVIRONMENT VARIABLES

See environ(7) for descriptions of the following environment
variables that affect the execution of touch: LANG, LC_ALL, LANG,
LC_ALL, LC_CTYPE, LC_MESSAGES, and NLSPATH.

TZ

Determine the timezone to be used for interpreting the time or
date_time option-argument or the time_spec operand.

EXIT STATUS

The following exit values are returned:

0

The touch utility executed successfully and all requested changes
were made.

>0

An error occurred. The touch utility returned the number of files
for which the times could not be successfully modified.

ATTRIBUTES

NOTES

Users familiar with the BSD environment find that for the touch
utility, the -f option is accepted but ignored. The -f option is
unnecessary because touch succeeds for all files owned by the user
regardless of the permissions on the files.

June 13, 2021 TOUCH(1)