blocks|key|2390931|text|此脚本可能会帮助您：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2390932|+++read+-p+"enter+group+name:+"+group
+++if+grep+-q+$group+/etc/group
++++then
+++++++++echo+"group+exists"
++++else
+++++++++echo+"group+does+not+exist"
++++fi|code-block|syntax|javascript|2390933|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

This script may help you:

<pre><code> read -p "enter group name: " group
 if grep -q $group /etc/group
 then
 echo "group exists"
 else
 echo "group does not exist"
 fi
</code></pre>

blocks|key|5215718|text|grep语句在rups解决方案中存在一些缺陷：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|5215719|例如，组grepping+admin在存在组lpadmin时可以返回true+(“组存在”)。|5215720|要么修复grep-query|5215721|grep+-q+-E+"%5Eadmin:"+/etc/group|code-block|syntax|javascript|5215722|或使用|5215723|if+[+$(getent+group+admin)+];+then
++echo+"group+exists."
else
++echo+"group+does+not+exist."
fi|5215724|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/users/2481010/rups^0|0|4|7|4|0|0|4|8|D|5|M|7|Y|4|0|4|4|0|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@$9|11|A|12|B|C]]|D|@$9|13|A|14|1|15]]|E|$]]|$1|F|3|G|5|6|7|16|8|@$9|17|A|18|B|C]|$9|19|A|1A|B|C]|$9|1B|A|1C|B|C]|$9|1D|A|1E|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|1F|8|@$9|1G|A|1H|B|C]]|D|@]|E|$]]|$1|J|3|K|5|L|7|1I|8|@]|D|@]|E|$M|N]]|$1|O|3|P|5|6|7|1J|8|@]|D|@]|E|$]]|$1|Q|3|R|5|L|7|1K|8|@]|D|@]|E|$M|N]]|$1|S|3|-4|5|6|7|1L|8|@]|D|@]|E|$]]]|T|$U|$5|V|W|X|E|$Y|Z]]]]

The <code>grep</code> statement in the solution of <a href="https://stackoverflow.com/users/2481010/rups">rups</a> has some flaws:

E.g. <code>grepping</code> for a group <code>admin</code> may return <code>true</code> ("group exists") when there is a group <code>lpadmin</code>.

Either fix the <code>grep</code>-query

<pre><code>grep -q -E "^admin:" /etc/group
</code></pre>

or use

<pre class="lang-sh prettyprint-override"><code>if [ $(getent group admin) ]; then
 echo "group exists."
else
 echo "group does not exist."
fi
</code></pre>

blocks|key|2391015|text|Grepping+/etc/group工作，但仅在/etc/nsswitch.conf具有：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2391016|group:+files|code-block|syntax|javascript|2391017|这意味着在确定可用组时只会咨询/etc/group。使用其中任何一种(按名称或按gid)：|2391018|getent+group+<groupname>
getent+group+<groupid>|2391019|对于更一般的解决方案，检查退出状态:0表示“存在”，非零表示“不存在”。例如，要检查组'postgres‘是否存在，如果不存在，则创建它(假设bash+shell，以能够创建新组的用户身份运行)运行：|2391020|/usr/bin/getent+group+postgres+2>&1+>+/dev/null+%7C%7C+/usr/sbin/groupadd+postgres|2391021|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

Grepping /etc/group works, but only on a machine where /etc/nsswitch.conf has:
<pre><code>group: files
</code></pre>
meaning that only /etc/group is consulted when determining available groups. Use either of these (by name or by gid):
<pre><code>getent group &lt;groupname&gt;
getent group &lt;groupid&gt;
</code></pre>
for a more generic solution, checking the exit status: 0 means &quot;exists&quot;, non-zero means &quot;does not exist&quot;. For example, to check to see if group 'postgres' exists, and create it if it does not (assuming bash shell, running as a user able to create new groups) run:
<pre><code>/usr/bin/getent group postgres 2&gt;&amp;1 &gt; /dev/null || /usr/sbin/groupadd postgres
</code></pre>

blocks|key|5215808|text|我发现将andiba的解决方案组合成一个适当的函数更有用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5215809|function+grpexists+{
++++if+[+$(getent+group+$1)+];+then
++++++echo+"group+$1+exists."
++++else
++++++echo+"group+$1+does+not+exist."
++++fi
}|code-block|syntax|javascript|5215810|这可以通过在您的/etc/bash.bashrc*中包含此函数来调用到您的环境中，这样您就可以使用以下拼写检查是否存在一个组：|offset|length|style|CODE|5215811|grpexists+group_name|5215812|然后返回下列其中之一：|5215813|群group_name存在。|blockquote|5215814|或|5215815|组group_name不存在。|5215816|entityMap^0|0|0|8|H|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Z|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|10|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|11|8|@$I|12|J|13|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|14|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|15|8|@]|9|@]|A|$]]|$1|Q|3|R|5|S|7|16|8|@]|9|@]|A|$]]|$1|T|3|U|5|6|7|17|8|@]|9|@]|A|$]]|$1|V|3|W|5|S|7|18|8|@]|9|@]|A|$]]|$1|X|3|-4|5|6|7|19|8|@]|9|@]|A|$]]]|Y|$]]

I've found it more useful, to compose andiba's solution into a proper function:

<pre class="lang-bash prettyprint-override"><code>function grpexists {
 if [ $(getent group $1) ]; then
 echo "group $1 exists."
 else
 echo "group $1 does not exist."
 fi
}
</code></pre>

This can for e.g be invoked into your environment by including this function in your <code>/etc/bash.bashrc*</code>, such that you can then check for the existence of a group, using the following spell:

<pre><code>grpexists group_name
</code></pre>

Which should then return one of:

<blockquote>
 group group_name exists.
</blockquote>

or

<blockquote>
 group group_name does not exist.
</blockquote>

blocks|key|5215834|text|下面是三个应该工作的命令：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5215835|group=sudo
grep+-qw+%5E$group+/etc/group+%7C%7C+groupadd+$group
usermod+-aG+$group+$USER|code-block|syntax|javascript|5215836|或者一个，当您使用-f/--force+(如果组已经存在的话成功退出)：|offset|length|style|CODE|5215837|groupadd+-f+mygroup+&&+usermod+-aG+mygroup+$USER|5215838|entityMap^0|0|0|9|2|C|7|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@$I|T|J|U|K|L]|$I|V|J|W|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|P|$]]

Here are 3 commands which should work:

<pre><code>group=sudo
grep -qw ^$group /etc/group || groupadd $group
usermod -aG $group $USER
</code></pre>

Or one, when you use <code>-f</code>/<code>--force</code> (exit successfully if the group already exists):

<pre><code>groupadd -f mygroup &amp;&amp; usermod -aG mygroup $USER
</code></pre>

blocks|key|2391112|text|极客们很棒的解决方案和指导，感谢大家在这里分享我的2分钱，让我们的生活变得更简单或更懒惰:-)我可以用来补充一个useradd脚本，我必须同时添加几个用户。我想知道几个组的for+in循环中会是什么样子:+group1、group2、group3...group6然后用户将类似这样的内容添加到系统中？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2391113|for+g+in+$(+cat+fewgroups.txt+);+do++++++++++groupadd+$g+++++++++++echo+"Group:"+$g+"Exist+not+added+moving+on"+++++++++else++++++++++echo+"Group:"+$g+"added+successfully!"++++++++++#+Then+create+the+users+++++++for+u+in+$(+cat+100sofusers.txt+);+do+++++++++useradd+-m+-g+group1+-G+group2,wheel+-d+/home/$u++-c+"Just+anothe+SiFiGeek"+-s+/bin/bash+$u++++++++++echo+"userID:"+$u+"added+successfully!"++++++++++echo+$u:$randompw+%7C+chpasswd++++++++++echo+"Password+for+userID:"+$u+"changed+successfully"+++++++done|offset|length|style|CODE|2391114|entityMap^0|0|0|E6|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@$D|L|E|M|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

Geeks great solutions and guidance, thanks for sharing here are my 2 cents to make our lives simpler or lazier :-) I could use to complement an useradd script I have to add several users at once. I'm wondering how it would look like inside a for 
 in loop for several groups: group1, group2, group3...group6
Then useradd to the system something like this?

<code>for g in $( cat fewgroups.txt ); do
 groupadd $g 
 echo "Group:" $g "Exist not added moving on"
 else
 echo "Group:" $g "added successfully!"
 # Then create the users
 for u in $( cat 100sofusers.txt ); do
 useradd -m -g group1 -G group2,wheel -d /home/$u -c "Just anothe SiFiGeek" -s /bin/bash $u
 echo "userID:" $u "added successfully!"
 echo $u:$randompw | chpasswd
 echo "Password for userID:" $u "changed successfully"
 done</code>

blocks|key|5215867|text|单行：|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|5215868|$getent组<-groupname->区组添加<--群名->|5215869|entityMap^0|0|3|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|M|8|@]|D|@]|E|$]]|$1|H|3|-4|5|6|7|N|8|@]|D|@]|E|$]]]|I|$]]

Single line: 
$getent group &lt;-groupname-> || groupadd &lt;-groupname->

blocks|key|5215871|text|$+groupadd+--help
Usage:+groupadd+[options]+GROUP

Options:
++-f,+--force+++++++++++++++++++exit+successfully+if+the+group+already+exists,
++++++++++++++++++++++++++++++++and+cancel+-g+if+the+GID+is+already+used|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|5215872|所以你可以简单地做：|unstyled|5215873|groupadd+-f+some_new_grp|5215874|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|L|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|I|3|-4|5|F|7|N|8|@]|9|@]|A|$]]]|J|$]]

<pre><code>$ groupadd --help
Usage: groupadd [options] GROUP

Options:
 -f, --force exit successfully if the group already exists,
 and cancel -g if the GID is already used
</code></pre>
So you can do simply:
<pre><code>groupadd -f some_new_grp
</code></pre>

this is a summary of what i want my code to do:

<pre><code>if (group exists)
then

 (add user to group)

else

 (create group)

 (add user to group)

fi
</code></pre>

I am using the Ubuntu virtual machine but all of the results i have found on similar sites do not work.

How to check if a group exists and add if it doesn't in Linux Shell Script

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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以下是我希望我的代码所做的工作的总结：if (group exists)then  (add user to group)else  (create group)  (add user to group)fi我正在使用Ubuntu虚拟机，但我在类似站点上发现的所有结果都不起作用。

问如何检查一个组是否存在，并在Linux脚本中添加它是否不存在
EN

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问如何检查一个组是否存在，并在Linux脚本中添加它是否不存在EN