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environ(7) [osx man page]

ENVIRON(7)					       BSD Miscellaneous Information Manual						ENVIRON(7)

NAME
environ -- user environment SYNOPSIS
extern char **environ; DESCRIPTION
An array of strings called the environment is made available by execve(2) when a process begins. By convention these strings have the form ``name=value''. The following names are used by various commands: BLOCKSIZE The size of the block units used by several commands, most notably df(1), du(1) and ls(1). BLOCKSIZE may be specified in units of a byte by specifying a number, in units of a kilobyte by specifying a number followed by ``K'' or ``k'', in units of a megabyte by specifying a number followed by ``M'' or ``m'' and in units of a gigabyte by specifying a number followed by ``G'' or ``g''. Sizes less than 512 bytes or greater than a gigabyte are ignored. EXINIT A startup list of commands read by ex(1) and vi(1). HOME A user's login directory, set by login(1) from the password file passwd(5). PATH The sequence of directories, separated by colons, searched by csh(1), sh(1), system(3), execvp(3), etc, when looking for an exe- cutable file. PATH is set to ``/usr/bin:/bin'' initially by login(1). PRINTER The name of the default printer to be used by lpr(1), lpq(1), and lprm(1). SHELL The full pathname of the user's login shell. TERM The kind of terminal for which output is to be prepared. This information is used by commands, such as nroff(1) which may exploit special terminal capabilities. See termcap(3) and terminfo(5). TMPDIR The directory in which to store temporary files. Most applications use either ``/tmp'' or ``/var/tmp''. Setting this variable will make them use another directory. TZ The timezone to use when displaying dates. The normal format is a pathname relative to ``/usr/share/zoneinfo''. For example, the command ``env TZ=US/Pacific date'' displays the current time in California. See tzset(3) for more information. LOGNAME The login name of the user. USER Deprecated synonym of LOGNAME (for backwards compatibility). Further names may be placed in the environment by the export command and name=value arguments in sh(1), or by the setenv command if you use csh(1). It is unwise to change certain sh(1) variables that are frequently exported by .profile files, such as MAIL, PS1, PS2, and IFS, unless you know what you are doing. PROGRAMMING
Programs can query and modify the environment, using the environment routines getenv(3), putenv(3), setenv(3) and unsetenv(3). Direct access can be made through the global variable environ, though it is recommended that changes to the enviroment still be made through the environ- ment routines. Shared libraries and bundles don't have direct access to environ, which is only available to the loader ld(1) when a complete program is being linked. The environment routines can still be used, but if direct access to environ is needed, the _NSGetEnviron() routine, defined in <crt_externs.h>, can be used to retrieve the address of environ at runtime. SEE ALSO
csh(1), ex(1), login(1), sh(1), getenv(3), putenv(3), setenv(3), unsetenv(3), execve(2), execle(3), system(3), termcap(3), terminfo(5) HISTORY
The environ manual page appeared in 4.2BSD. 4.2 Berkeley Distribution April 19, 1994 4.2 Berkeley Distribution

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ENVIRON(7)						 Miscellaneous Information Manual						ENVIRON(7)

NAME
environ - user environment SYNOPSIS
extern char *const *environ; DESCRIPTION
An array of strings called the `environment' is made available by execve(2) when a process begins. By convention these strings have the form `name=value'. The following names are used by various commands: PATH The sequence of directory prefixes that sh, time, nice(1), etc., apply in searching for a file known by an incomplete path name. The prefixes are separated by `:'. Login shells set PATH=:/bin:/usr/bin. Note that the empty space between the `=' and the `:' indicates the current directory. Security aware people move the extra `:' to the end of their path or omit it. HOME A user's login directory, set by login(1) from the password file passwd(5). TERM The kind of terminal for which output is to be prepared. This information is used by programs that wish to exploit special termi- nal capabilities, a screen oriented text editor for instance. The terminal type is set by login(1) from the tty database ttytab(5). SHELL The file name of the users login shell, set by login(1) from the password file passwd(5). TERMCAP The string describing the terminal in TERM, or the name of the termcap file, see termcap(5), termcap(3). EXINIT A startup list of commands read by elvis(1). USER The login name of the user, set by login(1) from the password file passwd(5). LOGNAME Set to the same value as USER. BSD derived systems have USER, System V has LOGNAME, so modern systems have both to avoid problems. Further names may be placed in the environment by the export command and `name=value' arguments in sh(1). Arguments may also be placed in their environment by programs if they use putenv(3). Or in the environment of another program by building a new environment for one of the exec functions that accepts an environment list, like execle(2) or execve(2). It is unwise to conflict with certain sh(1) variables that are frequently set and/or exported by `.profile' files: MAIL, PS1, PS2, IFS. SEE ALSO
elvis(1), login(1), sh(1), execl(2), execve(2), system(3), termcap(3), termcap(5), ttytab(5). 4.2 Berkeley Distribution May 20, 1985 ENVIRON(7)

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