ENVIRON(5)ENVIRON(5)NAMEenviron - user environment
DESCRIPTION
When a process begins execution, one of the exec family of functions
makes 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 pro‐
vide 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 one of the exec functions. It is
unwise to conflict with certain shell variables such as MAIL, PS1, PS2,
and IFS that are frequently exported by .profile files; 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 set‐
locale(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 invoked as setlo‐
cale(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 vari‐
able 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 vari‐
ables.
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 localedef(1) 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 indi‐
vidual character can be 1, 2, or 3 bytes wide; and EUC charac‐
ters of 1, 2, or 3 column widths. The default "C" locale corre‐
sponds 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 localedef()
command. This environment variable is used by ctype(3C),
mblen(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) com‐
mand. This environment variable is used by exstr(1), gettxt(1),
srchtxt(1), gettxt(3C), and gettext(3C).
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
localedef(1) 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 localedef() command. The default C
locale corresponds to "." as the decimal delimiter and no
thousands delimiter. This environment variable is used by
localeconv(3C), printf(3C), and strtod(3C).
LC_TIME
This category specifies date and time formats. The information
corresponding to this category is stored in a database speci‐
fied in localedef(). 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 administra‐
tor. A network identifier is also the first field in any /etc/net‐
config file entry. NETPATH thus provides a link into the /etc/net‐
config file and the information about a network contained in that
network's entry. /etc/netconfig is maintained by the system admin‐
istrator. The library routines described in getnetpath(3NSL) access
the NETPATH environment variable.
NLSPATH
Contains a sequence of templates which catopen(3C) and gettext(3C)
use when attempting to locate message catalogs. Each template con‐
sists 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 con‐
structed 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 or LC_MESSAGES.
%l
The language element from LANG or LC_MESSAGES.
%t
The territory element from LANG or LC_MESSAGES.
%c
The codeset element from LANG or LC_MESSAGES.
%%
A single % character.
An empty string is substituted if the specified value is not cur‐
rently 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 mes‐
sage catalog in name, name.cat and /nlslib/$LANG/name.cat. For get‐
text(), %N automatically maps to "messages".
If NLSPATH is unset or NULL, catopen() and gettext() call setlo‐
cale(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. The value of TZ has
one of the two formats (spaces inserted for clarity):
:characters
or
std offset dst offset, rule
If TZ is of the first format (that is, if the first character is a
colon (:)), or if TZ is not of the second format, then TZ desig‐
nates a path to a timezone database file relative to
/usr/share/lib/zoneinfo/, ignoring a leading colon if one exists.
Otherwise, TZ is of the second form, which when expanded is as fol‐
lows:
stdoffset[dst[offset][,start[/time],end[/time]]]
std and dst
Indicate no less than three, nor more than {TZNAME_MAX}, bytes
that are the designation for the standard (std) or the alterna‐
tive (dst, such as Daylight Savings Time) timezone. Only std is
required; if dst is missing, then the alternative time does not
apply in this timezone. Each of these fields can occur in
either of two formats, quoted or unquoted:
o In the quoted form, the first character is the less-
than ('<') character and the last character is the
greater-than ('>') character. All characters between
these quoting characters are alphanumeric characters
from the portable character set in the current
locale, the plus-sign ('+') character, or the minus-
sign ('-') character. The std and dst fields in this
case do not include the quoting characters.
o In the unquoted form, all characters in these fields
are alphabetic characters from the portable charac‐
ter set in the current locale.
The interpretation of these fields is unspecified if either
field is less than three bytes (except for the case when dst is
missing), more than {TZNAME_MAX} bytes, or if they contain
characters other than those specified.
offset
Indicate 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 can 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 dig‐
its can 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, must be between 0 and 59. Out of range
values can cause unpredictable behavior. If preceded by a "-",
the timezone is east of the Prime Meridian. Otherwise, it is
west of the Prime Meridian (which can 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 occurs. 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 Febru‐
ary 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 d^th 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 d^th day
occurs. Day zero is Sunday.
Implementation specific defaults are used for start and end if
these optional fields are not specified.
The time has the same format as offset except that no leading
sign ("-" or "+" ) is allowed. If time is not specified, the
default value is 02:00:00.
SEE ALSOcat(1), date(1), ed(1), fmtmsg(1), localedef(1), login(1), ls(1),
mkmsgs(1), nice(1), nohup(1), sh(1), sort(1), time(1), vi(1), exec(2),
addseverity(3C), catopen(3C), ctime(3C), ctype(3C), fmtmsg(3C), get‐
date(3C), getnetpath(3NSL), gettext(3C), gettxt(3C), localeconv(3C),
mblen(3C), mktime(3C), printf(3C), setlocale(3C), strcoll(3C), strf‐
time(3C), strtod(3C), strxfrm(3C), TIMEZONE(4), netconfig(4),
passwd(4), profile(4)
Nov 19, 2002 ENVIRON(5)