Linux locate 命令

在 Linux 中可能有时候需要查询磁盘上某个文件在什么位置，可能只是知道文件名，大多数情况通过 find 命令是可以解决问题，但是 find 命令在于每次都需要遍历磁盘文件树速度，所以文件越多速度就越慢，并且由于 find 功能尤为强大参数较多。有没有一个命令能快速查找，又简单明了，locate 就是解决这个问题的。

$ time find / -path *apache*
/var/lib/selinux/targeted/active/modules/100/apache
/var/lib/selinux/targeted/active/modules/100/apache/hll
/var/lib/selinux/targeted/active/modules/100/apache/lang_ext
/var/lib/selinux/targeted/active/modules/100/apache/cil
/usr/share/selinux/targeted/default/active/modules/100/apache
/usr/share/selinux/targeted/default/active/modules/100/apache/lang_ext
/usr/share/selinux/targeted/default/active/modules/100/apache/cil
/usr/share/bash-completion/completions/apache2ctl
/usr/lib/python3.6/site-packages/sos/report/plugins/apache.py
/usr/lib/python3.6/site-packages/sos/report/plugins/__pycache__/apache.cpython-36.pyc
/usr/lib/python3.6/site-packages/sos/report/plugins/__pycache__/apache.cpython-36.opt-1.pyc

real    0m1.254s
user    0m0.419s
sys 0m0.717s

$ time locate apache
/usr/lib/python3.6/site-packages/sos/report/plugins/apache.py
/usr/lib/python3.6/site-packages/sos/report/plugins/__pycache__/apache.cpython-36.opt-1.pyc
/usr/lib/python3.6/site-packages/sos/report/plugins/__pycache__/apache.cpython-36.pyc
/usr/share/bash-completion/completions/apache2ctl
/usr/share/selinux/targeted/default/active/modules/100/apache
/usr/share/selinux/targeted/default/active/modules/100/apache/cil
/usr/share/selinux/targeted/default/active/modules/100/apache/lang_ext
/var/lib/selinux/targeted/active/modules/100/apache
/var/lib/selinux/targeted/active/modules/100/apache/cil
/var/lib/selinux/targeted/active/modules/100/apache/hll
/var/lib/selinux/targeted/active/modules/100/apache/lang_ext

real    0m0.141s
user    0m0.130s
sys 0m0.007s

如果提示没有 .db 文件，updatedb 可以生成 .db 文件，首次会比较慢

我的磁盘文件较少，这其中查询速度就已经相差一个数量级。
locate 还有一些其他参数

• 查询文件名

$ locate -b  apache 
/usr/lib/python3.6/site-packages/sos/report/plugins/apache.py
/usr/lib/python3.6/site-packages/sos/report/plugins/__pycache__/apache.cpython-36.opt-1.pyc
/usr/lib/python3.6/site-packages/sos/report/plugins/__pycache__/apache.cpython-36.pyc
/usr/share/bash-completion/completions/apache2ctl
/usr/share/selinux/targeted/default/active/modules/100/apache
/var/lib/selinux/targeted/active/modules/100/apache

b 是 basename

• 统计数量

$ locate -b -c  apache
6

• 忽视大小写

$ locate -i apache
/usr/lib/python3.6/site-packages/sos/report/plugins/apache.py
/usr/lib/python3.6/site-packages/sos/report/plugins/__pycache__/apache.cpython-36.opt-1.pyc
/usr/lib/python3.6/site-packages/sos/report/plugins/__pycache__/apache.cpython-36.pyc
/usr/share/bash-completion/completions/apache2ctl
/usr/share/selinux/targeted/default/active/modules/100/apache
/usr/share/selinux/targeted/default/active/modules/100/apache/cil
/usr/share/selinux/targeted/default/active/modules/100/apache/lang_ext
/var/lib/docker/overlay2/116ff1a457689fa9d31f045d4bb7d04d8791308e3ce6bb28b806d0634f5a580e/diff/usr/share/perl/5.20.2/CGI/Apache.pm
/var/lib/docker/overlay2/236df4c36580d0f590b7beb2421720a0afa9dc4459bc7fb7d9e6f9f1fc41d75c/diff/usr/share/common-licenses/Apache-2.0
/var/lib/docker/overlay2/2f0479cc846777a9c4f650680be86346cdda6ed1b040947e87324fab4e86034f/diff/usr/share/common-licenses/Apache-2.0
/var/lib/docker/overlay2/b899ddfdb2940ae3c37e654ed23c93c704365a9ea5599e0000123167a026b3d6/diff/usr/share/common-licenses/Apache-2.0
/var/lib/selinux/targeted/active/modules/100/apache
/var/lib/selinux/targeted/active/modules/100/apache/cil
/var/lib/selinux/targeted/active/modules/100/apache/hll
/var/lib/selinux/targeted/active/modules/100/apache/lang_ext

• 通过正则表达式查询

$ locate -i  -r apache.py$
/usr/lib/python3.6/site-packages/sos/report/plugins/apache.py

Tip

但是 locate 也有一个问题在于如果文件被删除，locate 数据库还没有刷新的话，就会存在查找的文件已不再磁盘上，这个时候可以添加另外一个参数解决 -e，但是更为合适做法是配置 cronjob，定时更新 locate 数据库。

$ updatedb  

$ locate -S
数据库 /var/lib/mlocate/mlocate.db:
    20,215 文件夹
    174,859 文件
    18,633,061 文件名中的字节数
    4,898,343 字节用于存储数据库

updatedb 更新数据库，locate -S 数据库统计。