Linux Memo Recorder

Miscellaneous Records

• Ubuntu /etc/network/interfaces does not seem to take effect by modifying the IP and restarting the network service. You can restart the computer for it to take effect, or perform:

• Generate random Characters/numbers:

  • Using a Linux built-in variable $RANDOM , the variable will randomly output 0-32767 a range of numbers.
    ' shell 随机输出0-255范围的数字 echo expr $RANDOM/128 '

  Random output 1-255 range of numbers
  Echoexpr $RANDOM / 129 + 1
  ```

• Tar package specified directory (relative path)

  tarthe "absolute path" is displayed when you use a packaged file/directory for decompression. Example: Pack now /etc/sysconfig/ , /var/log two directories

  [[email protected] tmp]# tar -zcpf test.tgz /etc/sysconfig /var/log[[email protected] tmp]# tar -zxf test.tgz [[email protected] tmp]# lsetc  test.tgz  var

  You can see tar that it is packaged by an absolute path. To package only sysconfig and log two directories, use the -C parameters

  [[email protected] tmp]# tar -zcpf test.tgz -C /etc sysconfig -C /var log[[email protected] tmp]# tar -zxf test.tgz [[email protected] tmp]# lslog  sysconfig  test.tgz

• sedString Case Conversion

  大写转小写：echo ‘ABC‘ | sed ‘s/[A-Z]/\l&\g‘小写转大写：echo ‘abc‘ | sed ‘s/[a-z]/\u&\g‘

• sedMultiple substitutions

  example, capitalize the string ABcd3+4/ZZ to lowercase, and remove the punctuation ([:p UNCT:] is a collection of punctuation marks):

  $ echo ‘ABcd3+4/ZZ‘ | sed ‘s/[0-9]//g;s/[A-Z]/\l&/g;s/[[:punct:]]//g‘abcdzz

Linux Memo Recorder