Linux基础命令之getent

getent命令简述

getent - get entries（entry的复数，条目、项目、记载、记录）

getent命令可以用来察看系统的数据库中的相关记录

经常使用getent查看用户账号：

• 之前实验我们创建了一个UID为211的apahce系统账号，我们现在要查看apahce账号的信息
• 通常的做法是我们cat etc下的passwd得到账号apache信息
• 因为passwd也是系统的一种数据库，我们这时候就可以使用getent命令查看

[23:04:08 root@C8[ ~]#cat /etc/passwd | grep apahce
apahce:x:211:211:Apahce211:/var/www:/sbin/nologin
[23:04:14 root@C8[ ~]#getent passwd apahce
apahce:x:211:211:Apahce211:/var/www:/sbin/nologin

---

[22:57:00 root@C8[ ~]#getent --help
Usage: getent [OPTION...] database [key ...]
Get entries from administrative database.

  -i, --no-idn               disable IDN encoding
  -s, --service=CONFIG       Service configuration to be used
  -?, --help                 Give this help list
      --usage                Give a short usage message
  -V, --version              Print program version

Mandatory or optional arguments to long options are also mandatory or optional
for any corresponding short options.

Supported databases:

ahosts ahostsv4 ahostsv6 aliases ethers group gshadow hosts initgroups

netgroup networks passwd protocols rpc services shadow

For bug reporting instructions, please see:

http://www.gnu.org/software/libc/bugs.html.

[23:04:48 root@C8[ ~]#man getent

GETENT(1)                                                User Commands                                               GETENT(1)

NAME
       getent - get entries from Name Service Switch libraries

SYNOPSIS
       getent [option]... database key...

DESCRIPTION
       The getent command displays entries from databases supported by the Name Service Switch libraries, which are configured
       in /etc/nsswitch.conf.  If one or more key arguments are provided, then only the entries that match the  supplied  keys
       will  be displayed.  Otherwise, if no key is provided, all entries will be displayed (unless the database does not sup‐
       port enumeration).

       The database may be any of those supported by the GNU C Library, listed below:

          ahosts    When no key is provided, use sethostent(3), gethostent(3), and endhostent(3) to enumerate the hosts  data‐
                    base.   This  is  identical to using hosts.  When one or more key arguments are provided, pass each key in
                    succession to getaddrinfo(3) with the address family AF_UNSPEC, enumerating each socket address  structure
                    returned.

          ahostsv4  Same as ahosts, but use the address family AF_INET.

          ahostsv6  Same as ahosts, but use the address family AF_INET6.  The call to getaddrinfo(3) in this case includes the
                    AI_V4MAPPED flag.

          aliases   When no key is provided, use setaliasent(3), getaliasent(3), and endaliasent(3) to enumerate  the  aliases
                    database.   When  one or more key arguments are provided, pass each key in succession to getaliasbyname(3)
                    and display the result.

          ethers    When one or more key arguments are provided, pass each key in succession to ether_aton(3) and  ether_host‐
                    ton(3)  until  a result is obtained, and display the result.  Enumeration is not supported on ethers, so a
                    key must be provided.

          group     When no key is provided, use setgrent(3), getgrent(3), and endgrent(3) to enumerate  the  group  database.
                    When  one or more key arguments are provided, pass each numeric key to getgrgid(3) and each nonnumeric key
                    to getgrnam(3) and display the result.

          gshadow   When no key is provided, use setsgent(3), getsgent(3), and endsgent(3) to enumerate the gshadow  database.
                    When  one  or  more key arguments are provided, pass each key in succession to getsgnam(3) and display the
                    result.

          hosts     When no key is provided, use sethostent(3), gethostent(3), and endhostent(3) to enumerate the hosts  data‐
                    base.   When  one  or  more  key  arguments  are provided, pass each key to gethostbyaddr(3) or gethostby‐
                    name2(3), depending on whether a call to inet_pton(3) indicates that the key is an IPv6 or IPv4 address or
                    not, and display the result.

          initgroups
                    When  one  or  more key arguments are provided, pass each key in succession to getgrouplist(3) and display
                    the result.  Enumeration is not supported on initgroups, so a key must be provided.

          netgroup  When one key is provided, pass the key to setnetgrent(3) and, using getnetgrent(3) display  the  resulting
                    string  triple  (hostname,  username,  domainname).   Alternatively, three keys may be provided, which are
                    interpreted as the hostname, username and domainname to match to a netgroup name via innetgr(3).  Enumera‐
                    tion is not supported on netgroup, so either one or three keys must be provided.

          networks  When  no key is provided, use setnetent(3), getnetent(3), and endnetent(3) to enumerate the networks data‐
                    base.  When one or more key arguments are provided, pass each numeric key to getnetbyaddr(3) and each non‐
                    numeric key to getnetbyname(3) and display the result.

          passwd    When  no  key is provided, use setpwent(3), getpwent(3), and endpwent(3) to enumerate the passwd database.
                    When one or more key arguments are provided, pass each numeric key to getpwuid(3) and each nonnumeric  key
                    to getpwnam(3) and display the result.

          protocols When no key is provided, use setprotoent(3), getprotoent(3), and endprotoent(3) to enumerate the protocols
                    database.  When one or more key arguments are provided, pass each numeric key to  getprotobynumber(3)  and
                    each nonnumeric key to getprotobyname(3) and display the result.

          rpc       When  no  key is provided, use setrpcent(3), getrpcent(3), and endrpcent(3) to enumerate the rpc database.
                    When one or more key arguments are provided, pass each numeric key to getrpcbynumber(3)  and  each  nonnu‐
                    meric key to getrpcbyname(3) and display the result.

          services  When  no  key  is  provided, use setservent(3), getservent(3), and endservent(3) to enumerate the services
                    database.  When one or more key arguments are provided, pass each numeric key  to  getservbynumber(3)  and
                    each nonnumeric key to getservbyname(3) and display the result.

          shadow    When  no  key is provided, use setspent(3), getspent(3), and endspent(3) to enumerate the shadow database.
                    When one or more key arguments are provided, pass each key in succession to getspnam(3)  and  display  the
                    result.

OPTIONS
       -s service, --service service
              Override all databases with the specified service.  (Since glibc 2.2.5.)

       -s database:service, --service database:service
              Override  only  specified databases with the specified service.  The option may be used multiple times, but only
              the last service for each database will be used.  (Since glibc 2.4.)

       -i, --no-idn
              Disables IDN encoding in lookups for ahosts/getaddrinfo(3) (Since glibc-2.13.)

       -?, --help
              Print a usage summary and exit.

       --usage
              Print a short usage summary and exit.

       -V, --version
              Print the version number, license, and disclaimer of warranty for getent.

EXIT STATUS
       One of the following exit values can be returned by getent:

          0         Command completed successfully.

          1         Missing arguments, or database unknown.

          2         One or more supplied key could not be found in the database.

          3         Enumeration not supported on this database.

SEE ALSO
       nsswitch.conf(5)

COLOPHON
       This page is part of release 4.15 of the Linux man-pages project.  A description  of  the  project,  information  about
       reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

Linux                                                     2015-04-19