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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><!-- Copyright 1997 The Open Group, All Rights Reserved --><title>newgrp</title></head><body bgcolor=white><center><font size=2>The Single UNIX ® Specification, Version 2<br>Copyright © 1997 The Open Group</font></center><hr size=2 noshade><h4><a name = "tag_001_014_1498"> </a>NAME</h4><blockquote>newgrp - change to a new group</blockquote><h4><a name = "tag_001_014_1499"> </a>SYNOPSIS</h4><blockquote><pre><code>newgrp <b>[</b>-l<b>][</b><i>group</i>newgrp <b>[</b>-<b>][</b><i>group</i><b>]</b></code></pre></blockquote><h4><a name = "tag_001_014_1500"> </a>DESCRIPTION</h4><blockquote>The<i>newgrp</i>utility creates a newshell execution environmentwith a new real and effective group identification.Of the attributes listed in<xref href=shexenv><a href="chap2.html#tag_001_012">Shell Execution Environment</a></xref>,the new shell execution environment will retainthe working directory, file creation maskand exported variables from the previous environment(that is, open files, traps, unexported variables,alias definitions, shell functions and<i>set</i>options may be lost).All other aspects of the process environment that are preserved by the<i>exec</i>family of functions in the <b>XSH</b> specificationalso are preserved by<i>newgrp</i>;whether other aspects are preserved is unspecified.<p>A failure to assign the new group identifications (for example, for securityor password-related reasons) does not prevent the new shell executionenvironment from being created.<p>The<i>newgrp</i>utility affects the supplemental groups for the process as follows:<ul><p><li>On systems where the effective group ID is normally in the supplementarygroup list (or whenever the old effective group ID actually is in thesupplementary group list):<ul><p><li>If the new effective group ID is also in the supplementary group list,<i>newgrp</i>will change the effective group ID.<p><li>If the new effective group ID is not in the supplementary group list,<i>newgrp</i>will add the new effective group ID to the list, if there is room to add it.<p></ul><p><li>On systems where the effective group ID is not normally in the supplementarygroup list (or whenever the old effective group ID is not in thesupplementary group list):<ul><p><li>If the new effective group ID is in the supplementary group list,<i>newgrp</i>will delete it.<p><li>If the old effective group ID is not in the supplementary list,<i>newgrp</i>will add it if there is room.<p></ul><p></ul><dl><dt><b>Note:</b><dd>The <b>XSH</b> specification does not specify whether the effective group ID of a process isincluded in its supplementary group list.</dl>With no operands,<i>newgrp</i>will change the effective group back tothe groups identified in the user's user entry, andwill set the list of supplementary groups to that setin the user's group database entries.<p>If a password is required for the specified group, and theuser is not listed as a member of that groupin the group database, the user willbe prompted toenter the correct password for that group.If the user islisted as a member of that group, no password will be requested.If no password is required for the specified group,it is implementation-dependent whetherusers not listed as members of that group can change to that group.Whether or not a password is required, implementation-dependentsystem accounting or security mechanisms may impose additional authorisationrestrictions that may cause<i>newgrp</i>to write a diagnostic message and suppress the changing of the groupidentification.<br></blockquote><h4><a name = "tag_001_014_1501"> </a>OPTIONS</h4><blockquote>The<i>newgrp</i>utility supports the <b>XBD</b> specification, <a href="../xbd/utilconv.html#usg"><b>Utility Syntax Guidelines</b> </a> , exceptthat the obsolescent version uses "-" in a non-standard manner.<p>The following option is supported:<dl compact><dt><b>-l</b><dd>(The letter ell.)<dt><b>-</b><dd>Change the environment to what would be expected if theuser actually logged in again.</dl></blockquote><h4><a name = "tag_001_014_1502"> </a>OPERANDS</h4><blockquote>The following operand is supported:<dl compact><dt><i>group</i><dd>A group name from the group database or a non-negative numeric group ID.Specifies the group ID to which the real and effective group IDswill be set.If<i>group</i>is a non-negative numeric string and exists in thegroup database as a group name (see<i><a href="../xsh/getgrnam.html">getgrnam()</a></i>),the numeric group ID associated with that group name will be used asthe group ID.</dl></blockquote><h4><a name = "tag_001_014_1503"> </a>STDIN</h4><blockquote>Not used.</blockquote><h4><a name = "tag_001_014_1504"> </a>INPUT FILES</h4><blockquote>The file<b>/dev/tty</b>is used to read a single line of text for password checking,when one is required.</blockquote><h4><a name = "tag_001_014_1505"> </a>ENVIRONMENT VARIABLES</h4><blockquote>The following environment variables affect the execution of<i>newgrp</i>:<dl compact><dt><i>LANG</i><dd>Provide a default value for the internationalisation variablesthat are unset or null.If<i>LANG</i>is unset or null, the corresponding value from theimplementation-dependent default locale will be used.If any of the internationalisation variables contains an invalid setting, theutility will behave as if none of the variables had been defined.<dt><i>LC_ALL</i><dd>If set to a non-empty string value,override the values of all the other internationalisation variables.<dt><i>LC_CTYPE</i><dd>Determine thelocale for the interpretation of sequences of bytes of text data ascharacters (for example, single- as opposed to multi-byte charactersin arguments).<dt><i>LC_MESSAGES</i><dd>Determine the locale that should be used to affectthe format and contents of diagnosticmessages written to standard error.<dt><i>NLSPATH</i><dd>Determine the location of message cataloguesfor the processing of<i>LC_MESSAGES .</i></dl></blockquote><h4><a name = "tag_001_014_1506"> </a>ASYNCHRONOUS EVENTS</h4><blockquote>Default.</blockquote><h4><a name = "tag_001_014_1507"> </a>STDOUT</h4><blockquote>Not used.</blockquote><h4><a name = "tag_001_014_1508"> </a>STDERR</h4><blockquote>Used for diagnostic messages anda prompt string for a password, if one is required.Diagnostic messages may be written in cases where the exit status is notavailable; see <b>EXIT STATUS</b>.</blockquote><h4><a name = "tag_001_014_1509"> </a>OUTPUT FILES</h4><blockquote>None.</blockquote><h4><a name = "tag_001_014_1510"> </a>EXTENDED DESCRIPTION</h4><blockquote>None.</blockquote><h4><a name = "tag_001_014_1511"> </a>EXIT STATUS</h4><blockquote>If<i>newgrp</i>succeeds in creating a new shell execution environment, whether or not thegroup identification was changed successfully,the exit status will be the exit status of the shell.Otherwise, the following exit value is returned:<dl compact><dt>>0<dd>An error occurred.</dl></blockquote><h4><a name = "tag_001_014_1512"> </a>CONSEQUENCES OF ERRORS</h4><blockquote>The invoking shell may terminate.</blockquote><h4><a name = "tag_001_014_1513"> </a>APPLICATION USAGE</h4><blockquote>There is no convenient way to enter a password intothe Group Database.Use of group passwords is not encouraged,because by their very nature they encourage poor security practices.Group passwords may disappear in the future.<p>A common implementation of<i>newgrp</i>is that the current shell uses<i>exec</i>to overlay itself with<i>newgrp</i>,which in turn overlaysitself with a new shell after changing group.On some systems, however, this may not occur and<i>newgrp</i>may be invoked as a subprocess.<p>The<i>newgrp</i>commandis intended only for use from an interactive terminal.It does not offer a useful interface for the support of applications.<p>The exit status of<i>newgrp</i>is generally inapplicable. If<i>newgrp</i>is used in a script, in most cases it will successfully invoke a new shelland the rest of the original shell script will be bypassed when the newshell exits.Used interactively,<i>newgrp</i>displays diagnostic messages to indicate problems.But usage such as:<pre><code>newgrp fooecho $?</code></pre>is not useful because the new shell might not have access to any status<i>newgrp</i>may have generated (and most historical systems do not provide this status).A zero status echoed here does not necessarily indicate that the user haschanged to the new group successfully.Following<i>newgrp</i>with the<i><a href="id.html">id</a></i>command provides a portable means of determiningwhether the group change was successful or not.</blockquote><h4><a name = "tag_001_014_1514"> </a>EXAMPLES</h4><blockquote>None.</blockquote><h4><a name = "tag_001_014_1515"> </a>FUTURE DIRECTIONS</h4><blockquote>None.</blockquote><h4><a name = "tag_001_014_1516"> </a>SEE ALSO</h4><blockquote><i><a href="sh.html">sh</a></i>,the <b>XSH</b> specification description of<i>exec</i>.</blockquote><hr size=2 noshade><center><font size=2>UNIX ® is a registered Trademark of The Open Group.<br>Copyright © 1997 The Open Group<br> [ <a href="../index.html">Main Index</a> | <a href="../xshix.html">XSH</a> | <a href="../xcuix.html">XCU</a> | <a href="../xbdix.html">XBD</a> | <a href="../cursesix.html">XCURSES</a> | <a href="../xnsix.html">XNS</a> ]</font></center><hr size=2 noshade></body></html>⌨️ 快捷键说明
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