Unix commands in Mac OS X

wanmin444

　　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.