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I know that that line above allows <user> to run sudo command without having to type in the password. But what does the syntax actually mean? If you can link to an article then that would be fine too. Thanks

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2 Answers 2

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From man sudoers

By default, sudo requires that a user authenticate him or herself before running a command. This behavior can be modified via the NOPASSWD tag

So users or groups are able to run sudo without authenticating. This makes it a big security risk so be very careful with this command.

Also check https://askubuntu.com/questions/334318/sudoers-file-enable-nopasswd-for-user-all-commands

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  • Thanks. What about ALL:(ALL)? I know it has something to do about users and groups but I don't understand Linux groups as it is so if you can help me out, that would be awesome. Oct 25, 2019 at 7:40
  • With that command, you just give ALL permissions. You must still authenticate. Oct 25, 2019 at 7:47
  • If you mean the exact function of the ALL=(ALL:ALL) ALL. The first ALL is the users allowed, the second one is the hosts, the third one is the user as you are running the command, the last one is the commands allowed. Check: unix.stackexchange.com/questions/201858/… Oct 25, 2019 at 7:48
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The sudoers man page describes this in great detail.

The format is;

user_spec host_spec=(runas_spec) NOPASSWD:cmd_spec 
  • user_spec identifies which users can use the rule.
  • host_spec identifies which hosts the rule applies to. This is optional and defaults to ALL.
  • runas_spec identifies which users the commands can be run as.
  • NOPASSWD: or PASSWD: specifies whether a password is required. This is optional and defaults PASSWD unless the default has been changed in sudoers configuration.
  • cmd_spec identifies which commands the rule can be run for.

It is common to use aliases for various specs. Each spec has a predefined alias ALL, which is self-explanatory.

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    The runas_spec and host_spec are switched here, it should be 'user_spec host_spec=(runas_spec) NOPASSWD:cmd_spec'
    – tetra
    Jun 2, 2020 at 6:32

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