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1.1 root 1: .TH ENVIRON 5
2: .CT 2 proc_man
3: .SH NAME
4: environ \- user environment
5: .SH SYNOPSIS
6: .B extern char **environ;
7: .SH DESCRIPTION
8: An array of strings called the `environment' is
9: made available by
10: .IR exec (2)
11: when a process begins.
12: By convention these strings have either the form
13: .IB name = value ,
14: defining a variable, or
15: .IB name (){ value } ,
16: defining a function; see
17: .IR sh (1).
18: The following variables are used by various commands:
19: .TF TERMCAP
20: .TP
21: .B PATH
22: The sequence of directory prefixes that
23: .I sh,
24: .IR time (1),
25: .IR nice (1),
26: etc.,
27: apply in searching for a file known by an incomplete path name.
28: The prefixes are separated by
29: .LR : .
30: .IR Login (8)
31: sets
32: .LR PATH=:/bin:/usr/bin .
33: .PD
34: .TP
35: .B HOME
36: A user's login directory, set by
37: .IR login (8)
38: from the password file
39: .IR passwd (5).
40: .TP
41: .B TERM
42: The kind of terminal for which output is to be prepared.
43: This information is used by commands, such as
44: .I nroff
45: or
46: .IR plot (1),
47: which may exploit special terminal capabilities.
48: Some customary values of
49: .B TERM
50: are
51: .BR 2621
52: (HP),
53: .BR 4014
54: (Tektronix),
55: .BR 5620
56: (Teletype), and
57: .BR 630
58: (Teletype).
59: See
60: .FR /etc/termcap ,
61: described in
62: .IR termcap (5),
63: for a longer list.
64: .TP
65: .B SHELL
66: The name of the login shell.
67: .PP
68: The environment may be queried by
69: .IR getenv (3)
70: or by the
71: .L set
72: or
73: .L whatis
74: commands of
75: .IR sh (1).
76: Names may be placed in the environment by the
77: .L export
78: command and by
79: .IB name = value
80: arguments of
81: .IR sh (1).
82: Names may also be placed in the environment at the point of an
83: .IR exec (2).
84: It is unwise to conflict with
85: certain
86: .IR sh (1)
87: variables that are frequently exported by
88: .F .profile
89: files:
90: .BR MAIL ,
91: .BR PS1 ,
92: .BR PS2 ,
93: .BR IFS .
94: .SH SEE ALSO
95: .IR sh (1),
96: .IR printenv (1),
97: .IR exec (2),
98: .IR getenv (3),
99: .IR term (6)
100: .SH BUGS
101: Function definitions in the environment break some old programs,
102: including old shells.
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