environ(5) manual page
Table of Contents
environ - user environment
When a process
begins execution, exec routines make available an array of strings called
the environment; see exec(2)
. By convention, these strings have the form
variable=value, for example, PATH
=/sbin:/usr/sbin. These environmental
variables provide a way to make information about a program’s environment
available to programs.
A name may be placed in the environment by the export
command and name=value arguments in sh(1)
, or by exec(2)
. It is unwise to
conflict with certain shell variables that are frequently exported by .profile
files: MAIL
, PS1
, PS2
, IFS
; see profile(4)
.
The following environmental
variables can be used by applications and are expected to be set in the
target run-time environment.
- HOME
- The name of the user’s login directory,
set by login(1)
from the password file; see passwd(4)
.
- LANG
- The string
used to specify internationalization information that allows users to work
with different national conventions. The setlocale(3C)
function checks the
LANG
environment variable when it is called with "" as the locale argument.
LANG
is used as the default locale if the corresponding environment variable
for a particular category is unset or null. If, however, LC_ALL
is set
to a valid, non-empty value, its contents are used to override both the
LANG
and the other LC_*
variables.
For example, when setlocale() is invoked
as
setlocale(LC_CTYPE, ""),
setlocale() will query the LC_CTYPE
environment variable first to see
if it is set and non-null. If LC_CTYPE
is not set or null, then setlocale()
will check the LANG
environment variable to see if it is set and non-null.
If both LANG
and LC_CTYPE
are unset or NULL
, the default "C" locale will
be used to set the LC_CTYPE
category.
- Most commands will invoke
setlocale(LC_ALL,
"")
- prior to any other processing.
- This allows the command to be used with
different national conventions by setting the appropriate environment variables.
- The following environment variables
- correspond to each category of setlocale(3C)
:
- LC_ALL
- If set to a valid, non-empty string value, override the values of
LANG
and all the other LC_*
variables.
- LC_COLLATE
- This category specifies
the character collation sequence being used. The information corresponding
to this category is stored in a database created by the colltbl(1M)
command.
This environment variable affects strcoll(3C)
and strxfrm(3C)
.
- LC_CTYPE
- This category specifies character classification, character conversion,
and widths of multibyte characters. When LC_CTYPE
is set to a valid value,
the calling utility can display and handle text and file names containing
valid characters for that locale; Extended Unix Code (EUC) characters
where any individual character can be 1, 2, or 3 bytes wide; and EUC characters
of 1, 2, or 3 column widths. The default "C" locale corresponds to the 7-bit
ASCII
character set; only characters from ISO 8859-1 are valid. The information
corresponding to this category is stored in a database created by the chrtbl(1M)
command. This environment variable is used by ctype(3C)
, mbchar(3C)
, and
many commands, such as cat(1)
, ed(1)
, ls(1)
, and vi(1)
.
- LC_MESSAGES
- This
category specifies the language of the message database being used. For
example, an application may have one message database with French messages,
and another database with German messages. Message databases are created
by the mkmsgs(1)
command. This environment variable is used by exstr(1)
,
gettxt(1)
, srchtxt(1)
, gettxt(3C)
, and gettext(3I)
.
- LC_MONETARY
- This category
specifies the monetary symbols and delimiters used for a particular locale.
The information corresponding to this category is stored in a database
created by the montbl(1M)
command. This environment variable is used by
localeconv(3C)
.
- LC_NUMERIC
- This category specifies the decimal and thousands
delimiters. The information corresponding to this category is stored in
a database created by the chrtbl(1M)
command. The default C
locale corresponds
to "." as the decimal delimiter and no thousands delimiter. This environment
variable is used by localeconv(3C)
, printf(3S)
, and strtod(3C)
.
- LC_TIME
- This category specifies date and time formats. The information corresponding
to this category is stored in a database specified in strftime(4)
. The default
C
locale corresponds to U.S. date and time formats. This environment variable
is used by many commands and functions; for example: at(1)
, calendar(1)
,
date(1)
, strftime(3C)
, and getdate(3C)
.
- MSGVERB
- Controls which standard format message components fmtmsg selects
when messages are displayed to stderr; see fmtmsg(1)
and fmtmsg(3C)
.
- NETPATH
- A colon-separated list of network identifiers. A network identifier is a
character string used by the Network Selection component of the system
to provide application-specific default network search paths. A network identifier
must consist of non-NULL
characters and must have a length of at least 1.
No maximum length is specified. Network identifiers are normally chosen
by the system administrator. A network identifier is also the first field
in any /etc/netconfig file entry. NETPATH
thus provides a link into the
/etc/netconfig file and the information about a network contained in that
network’s entry. /etc/netconfig is maintained by the system administrator.
The library routines described in getnetpath(3N)
access the NETPATH
environment
variable.
- NLSPATH
- Contains a sequence of templates which catopen(3C)
and
gettext(3I)
use when attempting to locate message catalogs. Each template
consists of an optional prefix, one or more substitution fields, a filename
and an optional suffix.
For example:
NLSPATH="/system/nlslib/%N.cat"
defines that catopen() should look for all message catalogs in the directory
/system/nlslib, where the catalog name should be constructed from the name
parameter passed to catopen(), %N, with the suffix .cat.
- Substitution fields
consist of a
- % symbol, followed by a single-letter keyword. The following
keywords are currently defined:
%N The value of the name parameter passed to
catopen().
%L The value of LANG.
%l The language element from LANG or LC_MESSAGES. %t The territory element
from LANG.
%c The codeset element from LANG.
%% A single % character.
An empty string is substituted if the specified value is not currently
defined. The separators ‘‘_’’ and ‘‘.’’ are not included in %t and %c substitutions.
- Templates defined in
- NLSPATH
are separated by colons (:). A leading colon
or two adjacent colons (::) is equivalent to specifying %N.
For example:
NLSPATH=":%N.cat:/nlslib/%L/%N.cat"
indicates to catopen() that it should look for the requested message catalog
in name, name.cat and /nlslib/$LANG/name.cat. For gettext(), %N automatically
maps to "messages".
- If
- NLSPATH
is unset or NULL
, catopen() and gettext() call setlocale(3C)
,
which checks LANG
and the LC_*
variables to locate the message catalogs.
- NLSPATH
- will normally be set up on a system wide basis (in /etc/profile)
and thus makes the location and naming conventions associated with message
catalogs transparent to both programs and users.
- PATH
- The sequence of directory
prefixes that sh(1)
, time(1)
, nice(1)
, nohup(1)
, and other utilities apply
in searching for a file known by an incomplete path name. The prefixes are
separated by colons (:). login(1)
sets PATH=/usr/bin. For more detail, see
sh(1)
.
- SEV_LEVEL
- Define severity levels and associate and print strings
with them in standard format error messages; see addseverity(3C)
, fmtmsg(1)
,
and fmtmsg(3C)
.
- TERM
- The kind of terminal for which output is to be prepared.
This information is used by commands, such as vi(1)
, which may exploit
special capabilities of that terminal.
- TZ
- Timezone information. The contents
of this environment variable are used by the functions ctime(3C)
, localtime(3C)
,
strftime(3C)
, and mktime(3C)
to override the default timezone. If TZ
is
not in the following form, it designates a path to a timezone database
file relative to /usr/share/lib/zoneinfo/, ignoring the first character
if it is a colon (:); otherwise, TZ
has the form:
stdoffset[dst[offset],[start[/time],end[/time]]]
- std and dst
- Three or more bytes that are the designation for the standard
(std) and daylight savings time (dst) timezones. Only std is required. If
dst is missing, then daylight savings time does not apply in this locale.
Upper- and lower-case letters are allowed. Any characters except a leading
colon (:), digits, a comma (,), a minus (-) or a plus (+) are allowed.
- offset
- Indicates the value one must add to the local time to arrive at Coordinated
Universal Time. The offset has the form:
hh[:mm[:ss]]
- The minutes
- (mm)
and seconds (ss) are optional. The hour (hh) is required and may be a single
digit. The offset following std is required. If no offset follows dst ,
daylight savings time is assumed to be one hour ahead of standard time.
One or more digits may be used; the value is always interpreted as a decimal
number. The hour must be between 0 and 24, and the minutes (and seconds)
if present between 0 and 59. Out of range values may cause unpredictable
behavior. If preceded by a ‘‘-’’, the timezone is east of the Prime Meridian;
otherwise it is west (which may be indicated by an optional preceding ‘‘+’’
sign).
- start/time,end/time
- Indicate when to change to and back from daylight
savings time, where start/time describes when the change from standard
time to daylight savings time occurs, and end/time describes when the change
back happens. Each time field describes when, in current local time, the
change is made.
- The formats of
- start and end are one of the following:
- Jn
- The Julian day n (1 <= n <= 365). Leap days are not counted. That is, in all
years, February 28 is day 59 and March 1 is day 60. It is impossible to
refer to the occasional February 29.
- n
- The zero-based Julian day (0 <= n <=
365). Leap days are counted, and it is possible to refer to February 29.
- Mm.n.d
- The duthd day, (0 <= d <= 6) of week n of month m of the year (1 <= n
<= 5, 1 <= m <= 12), where week 5 means ‘‘the last d-day in month m’’ which may
occur in either the fourth or the fifth week). Week 1 is the first week
in which the duthd day occurs. Day zero is Sunday.
- Implementation specific
defaults are used for
- start and end if these optional fields are not given.
- The
- time has the same format as offset except that no leading sign (‘‘-’’ or
‘‘+’’) is allowed. The default, if time is not given is 02:00:00.
cat(1)
,
date(1)
, ed(1)
, fmtmsg(1)
, login(1)
, ls(1)
, mkmsgs(1)
, nice(1)
, nohup(1)
,
sh(1)
, sort(1)
, time(1)
, vi(1)
, chrtbl(1M)
, colltbl(1M)
, montbl(1M)
, exec(2)
,
addseverity(3C)
, catopen(3C)
, ctime(3C)
, ctype(3C)
, fmtmsg(3C)
, getdate(3C)
,
getnetpath(3N)
, gettext(3I)
, gettxt(3C)
, localeconv(3C)
, mbchar(3C)
, mktime(3C)
,
printf(3S)
, setlocale(3C)
, strcoll(3C)
, strftime(3C)
, strtod(3C)
, strxfrm(3C)
,
netconfig(4)
, passwd(4)
, profile(4)
, strftime(4)
, TIMEZONE(4)
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