user_namespaces.7: Minor rewordings of recently added text

[thirdparty/man-pages.git] / man7 / environ.7

diff --git a/man7/environ.7 b/man7/environ.7
index 30f331405897ad77ede13cd0dc09ed43542b64ae..d9d80129d710e8a2517e736e007e86bb81ee699f 100644 (file)
--- a/man7/environ.7
+++ b/man7/environ.7
@@ -31,13 +31,12 @@
 .\" Modified Wed Jan 24 06:37:24 2001 by Eric S. Raymond (esr@thyrsus.com)
 .\" Modified Thu Dec 13 23:53:27 2001 by Martin Schulze <joey@infodrom.org>
 .\"
-.TH ENVIRON 7 2014-08-19 "Linux" "Linux Programmer's Manual"
+.TH ENVIRON 7 2017-09-15 "Linux" "Linux Programmer's Manual"
 .SH NAME
 environ \- user environment
 .SH SYNOPSIS
 .nf
 .BI "extern char **" environ ;
-.br
 .fi
 .SH DESCRIPTION
 The variable
@@ -53,7 +52,12 @@ feature test macro is defined.)
 This array of strings is made available to the process by the
 .BR exec (3)
 call that started the process.
-
+When a child process is created via
+.BR fork (2),
+it inherits a
+.I copy
+of its parent's environment.
+.PP
 By convention the strings in
 .I environ
 have the form "\fIname\fP\fB=\fP\fIvalue\fP".
@@ -124,14 +128,38 @@ The user's preferred utility to edit text files.
 .\" The user's preferred utility to browse URLs. Sequence of colon-separated
 .\" browser commands. See http://www.catb.org/~esr/BROWSER/ .
 .PP
-Further names may be placed in the environment by the
+Names may be placed in the shell's environment by the
 .I export
-command and "name=value" in
+command in
 .BR sh (1),
 or by the
 .I setenv
 command if you use
 .BR csh (1).
+.PP
+The initial environment of the shell is populated in various ways,
+such as definitions from
+.IR /etc/environment
+that are processed by
+.BR pam_env (8)
+for all users at login time (on systems that employ
+.BR pam (8)).
+In addition, various shell initialization scripts, such as the system-wide
+.IR /etc/profile
+script and per-user initializations script may include commands
+that add variables to the shell's environment;
+see the manual page of your preferred shell for details.
+.PP
+Bourne-style shells support the syntax
+.PP
+    NAME=value command
+.PP
+to create an environment variable definition only in the scope
+of the process that executes
+.IR command .
+Multiple variable definitions, separated by white space, may precede
+.IR command .
+.PP
 Arguments may also be placed in the
 environment at the point of an
 .BR exec (3).
@@ -141,11 +169,11 @@ A C program can manipulate its environment using the functions
 .BR setenv (3),
 and
 .BR unsetenv (3).
-
+.PP
 Note that the behavior of many programs and library routines is
 influenced by the presence or value of certain environment variables.
-A random collection:
-.LP
+Examples include the following:
+.IP * 3
 The variables
 .BR LANG ", " LANGUAGE ", " NLSPATH ", " LOCPATH ", "
 .BR LC_ALL ", " LC_MESSAGES ", "
@@ -154,34 +182,35 @@ and so on influence locale handling; see
 .BR gettext (3),
 and
 .BR locale (7).
-.LP
+.IP *
 .B TMPDIR
 influences the path prefix of names created by
-.BR tmpnam (3)
+.BR tempnam (3)
 and other routines, and the temporary directory used by
 .BR sort (1)
 and other programs.
-.LP
-.BR LD_LIBRARY_PATH ", " LD_PRELOAD
-and other LD_* variables influence
-the behavior of the dynamic loader/linker.
-.LP
+.IP *
+.BR LD_LIBRARY_PATH ", " LD_PRELOAD ,
+and other
+.BR LD_*
+variables influence the behavior of the dynamic loader/linker.
+.IP *
 .B POSIXLY_CORRECT
 makes certain programs and library routines follow
 the prescriptions of POSIX.
-.LP
+.IP *
 The behavior of
 .BR malloc (3)
 is influenced by
 .B MALLOC_*
 variables.
-.LP
+.IP *
 The variable
 .B HOSTALIASES
 gives the name of a file containing aliases
 to be used with
 .BR gethostbyname (3).
-.LP
+.IP *
 .BR TZ " and " TZDIR
 give timezone information used by
 .BR tzset (3)
@@ -192,24 +221,31 @@ and through that by functions like
 .BR strftime (3).
 See also
 .BR tzselect (8).
-.LP
+.IP *
 .B TERMCAP
 gives information on how to address a given terminal
 (or gives the name of a file containing such information).
-.LP
+.IP *
 .BR COLUMNS " and " LINES
 tell applications about the window size, possibly overriding the actual size.
-.LP
+.IP *
 .BR PRINTER " or " LPDEST
 may specify the desired printer to use.
 See
 .BR lpr (1).
+.SH NOTES
+The
+.BR prctl (2)
+.B PR_SET_MM_ENV_START
+and
+.B PR_SET_MM_ENV_END
+operations can be used to control the location of the process's environment.
 .SH BUGS
 Clearly there is a security risk here.
 Many a system command has been
 tricked into mischief by a user who specified unusual values for
 .BR IFS " or " LD_LIBRARY_PATH .
-
+.PP
 There is also the risk of name space pollution.
 Programs like
 .I make
@@ -243,9 +279,9 @@ The authors of
 should consider renaming their option to
 .BR GZIP_OPT .
 .SH SEE ALSO
-.BR env (1),
 .BR bash (1),
 .BR csh (1),
+.BR env (1),
 .BR login (1),
 .BR printenv (1),
 .BR sh (1),
@@ -254,9 +290,9 @@ should consider renaming their option to
 .BR clearenv (3),
 .BR exec (3),
 .BR getenv (3),
-.BR pam_env (3),
 .BR putenv (3),
 .BR setenv (3),
 .BR unsetenv (3),
 .BR locale (7),
-.BR ld.so (8)
+.BR ld.so (8),
+.BR pam_env (8)