Unix commands in Mac OS X

参考：http://www.renfei.org/blog/mac-os-x-terminal-101.html

One command line includes 4 parts: Command Name、Options、Arguments、Extras . 

man <command-name> :  Give the manual of this command.

绝对和相对路径

     / : Root directory

     ..  : Parent directory. 

目录操作

     pwd : Print working directory, which will show the absolute path of current folder.

     ls  : List directory contents.      Ls –la  : List all contents including hidden contents.

     cd : Change directory.

　  mkdir : Make directories.

     rmdir:  Remove directories.

　  mvdir:  Move or rename a directory.

      处理特殊字符(space, bracket, quotation mark, !, $, &, *, ;, \, …)

      \ : Use back slash before the character.        cd Punlic/Drop\ Box/      ( = cd “Public/Drop Box”).

文件操作

      cp  : Copy files.  

      mv : Move files.

      rm :  Remove files

      vi:  or vim :  A programmers text editor

      nano:  Nano‘s another editor, an enhanced free pico clone.

 　  cat : Concatenate and print files.  It reads files sequentially, writing them to the standard output.

               cat file1 : Will print the contents of file1 to the standard output.

               cat file1 file2 > file3:  Will sequentially print the cntents of file1 and file2 to the file3.

               cat file1 – file2 – file3:   ???

      od:  Octal, decimal, hex, ASCII dump

      less:

      which:  Locate a program file in the user’s path.

      find :   find . -name "*.c" -print

　   file:  Determine file type. 

      head:  Display first lines of a file.  head -10 filename.

　　tail:  Display the last part of a file. 

      cut:  Cut out selected portions of each lie of a flie.

      colrm:  Remove columns from a file.    colrm 8 20 filename

      diff: Compare files line by line.

      sort: Sort lines of text file.       

      uniq:  Report or filter out repeated lines in a file.

      comm: Select or regject lines common to two files.

      wc:  Word, line, character, and byte count.  

      nl: Line numbering filter.        nl file1 > file2

进程操作

　　ps : Process status     ps u

　　kill : Terminate or signal a process.               kill -9 30142

             The kill utility sends a signal to the processes specified by the pid operand(s).

　　　　 Only the super-user may send signals to other user‘s processes.

             Some of the more commonly used signals:

　　　　　　1　　HUP (hang up)

　　　　　　2　　INT (interrupt)

　　　　　　3　　QUIT

　　　　　　6　　 ABRT (abort)

　　　　　　9　　KILL (non-catchable, non-ignorable kill)

　　　　　　14 　　ALRM (alarm )

　　　　　　15　　TERM (software termination signal)

时间操作: 

　　date:　　Display or set date and time.

　　cal:  Display a calendar and the date of easter        cal 4 2015.   

      time: time command execution (totoal time elapsed.)

系统管理

      w:  Display who is logged in and what they are doing.

　　who: 

      whoami: 

      su  : Substitute user identify. 

      Sudo : Substitute user do, or super user do.  It allows a permitted user to execute a command as the superuser or another user.