4.Regular Expression （正则表达式）>>What is a regular expressionA regular expression is just a pattern of charactersused to match the same characters in a search.A regular expression can be controlled by special metacharacters.Regular Expressions can be used on:Commamd lines in ShellCommand lines in EditorsExample:|||==>regular expression:一般字符串一般字符 + 基本元字符:s/[Tt]om/David/Hi tom,I think I failed my anatomy test yesterday. I had a terriblestomach ache. I ate too many fried green tomatoes.Anyway, Tom, I need your help. I'd like to make the test uptomorrow, but don't know where to begin studying. Do youthink you could help me? After work, about 7 PM, come tomy place and I'll treat you to pizza in return for your help. Thanks. Your pal,guy@phantomIf you want to make a global substitutionto replace all occurrences of tom or Tom with David:Regular Expressions allow you to specify an expression that matches a pattern rather than a specific stringExample: /l..e//^love/ /love$// *love//[Ll]ove/ /[A-Z]ove/ /[^A-Z]//love\./Match lines with zero or>>Regular Expression Metacharacters.Matches one character^ Beginning-of-line anchor$ End-of-line anchor*Matches zero or more of the preceding characters[ ] Matches one in the set[x-y]Matches one character within a range in the set[^ ]Matches one character not in the set\Used to escape a metacharacter(在 shell 中一些元字符有特殊含义，\可以使其失去特殊含义)如：$ . ‘ “ * [ ] ^ | ( ) \ + ?I had a lovely time on our little picnic.Lovers were all around us. It is springtime. Ohlove, how much I adore you. Do you knowthe extent of my love? Oh, by the way, I thinkI lost my gloves somewhere out in that field ofclover. Did you see them? I can only hope loveis forever. I live for you. It's hard to get back in the /love//^love//love$//l.ve//o*ve//[Ll]ove/ /ove[a-z]/>>More Regular ExpressionsA matches a capital A[aeiou] matches any one of the vowelsz* matches z, zz, zzz, or a zfollowed by any number of z'sstop$ matches stop only if stop isthe last string on a line[35z] matches either 3, or 5, or z\^\$ matches the string ^$i.m matches i followed by any characterfollowed by m- iAm, or ibm, or i m, but not idiom5. Editorsed - line-oriented text editorex - line-oriented text editorsed - stream-oriented text editorvi - full-screen text editorvim - full-screen text editor ("vi-improved") emacs - screen-oriented text editor>>ed editorSyntax: ed [-s] [-p string] [filename]s - suppress printing of character counts, diagnostics,and the ? prompt when quitting without savingp string - use string as the editing prompt in command modeexample:ed new_file.txted Modes:Text mode interprets all input as text Command mode interprets all input as commands —— text input mode—— command mode Command mode can display a prompt,either a custom prompt with the -p string option on startup or the default (*) with the P commandText input mode displays no promptinitial:command modeEntering text input mode:—— using a (append) or i (insert)Exiting text input mode:—— using . (period) as the first character(and only character .) on a lineed Commands:-- Quitq To quit ed, enter a q in command mode-- Write back to the filew-- Undou Undo the last command-- Address in edYou always have a current address in ed-- Move Around in ed:p display current linenp display the line if it exists with line-number n3go to and display 3rd line1,4p go to line 4 and display lines from 1 to 4-3 go to the third line before the current line and display it ^p go to first line and display it$go to last line and display last line-- Add Texti places a line in front of the current line a places a line after the current line-- Delete Lines of Textd delete lines of text.The format of the command is#,#dd deletes the current line1,3d deletes lines 1 through 33,7d deletes lines 3 through 7.,$d deletes the lines from the current line through the end of the buffer1,$d deletes all lines in the buffer-- Delete & Insert with ChangeThe c (change) command deletes the line(s)given by the address range and then replaces themwith typed text.Normal form is #,#c where # is a line address-- Find & replaceThe format for s (substitute) is[#,#]s/find_expr/repl_expr/[g|n]s/sun/moon/ replace the first occurrence of "sun" with "moon"on the current line only1,5s/sun/moon/ do the same but for lines 1 - 51,5s/sun/moon/g replace all occurrences of "sun" with "moon"in lines 1 through 51,$s/sun/moon/g replace all occurrences of "sun" with "moon"in the entire bufferan errorcombines lines 10 through 14-- Combine Linesjjoin. j command requires the line numbersof two contiguous lines1,2j combines lines 1 and 210,11j combines lines 10 and 1110,14 because the lines are not contiguous -- Move Lines of Textm move lines.m requires an optional range of addresses to moveand a required address to move to.m4moves the current line behind line 41,3m$moves lines 1 through 3 to the end of the file m0moves the current line to the beginning m+ swaps the current line with the next line-- Copying Text with Transfert (transfer) command works similarly to the m commandexcept it copies the source linesrather than moving themt requires an optional range of addresses to copyand a required address to copy to.t. duplicate the current linet$ copies the current line to the end of the buffer1,$t$ duplicates the entire buffer at the end of the buffer 1,$t0 does the same only at the beginning of the buffer-- Marking LinesLines that you want to be able to refer to easilycan be marked using the k command[address]kxwhere address is an optional line address,default is current linex is any lower case letter-- Patterns and SearchesSearching is a powerful way to move about in edThe two common forms of searchesare forward searches and backwards searches/expr/ denotes a forward search?expr? denotes a backwards, or reverse searchSearches stop when they find the first occurrenceof expr (expr is often a regular expression) When the search is successful, it displays the lineand makes it the current linePreceding the search with a g (global) searchesand displays all lines containing expr - g/expr/ -- Read Files-- ......==> man ed>>ex editorex versus eded and ex have many similaritiesThey both use line addressesThey both use the same basic command setp, m, t, /expr/, ?expr?, r, w, q, d, u, ! command They also have some differences ......>>vi Visual Editorvi is a screen editor.Unlike MS-Word, or other word processors,vi files consist of plain ASCII textCommand line options:vi invokes vi with a blank buffervi file invokes vi on file or on a blank bufferusing file for the name if file does not exist vi file1 file2...invokes vi on files sequentiallyvi -R file invokes vi on file in read-only modeview file invokes vi on file in read-only modevi -r file recovers file and recent edits after asystem crash (or at least tries!)vi + file opens file with cursor at last linevi +n file opens file with cursor at line nvi +/expr file opens file with cursor at exprvi Architecture:——From vi command mode,Q switch to ex——From ex command mode:vi switch back to viChange from vi to ex and backvi is based on ex, All ex commands are available from within vivi is modalCommand and text entry modes—— enter text entry mode:ior aor [Insert] key—— return back to command mode:[Esc] key命令行模式：最后行模式：/exp ?exp n N #yy y3w p#p #dd dd. uZZJ#J:g/ pattern/p:s/[Hh]elp/HELP/& :#,#s/[Hh]elp/HELP/:#,#s/[Hh]elp/HELP/gc:w:w new_file.txt:q:q!:!ls:!!——添加、删除和修改文本—— 光标、屏幕控制——查找、查找下一个==>——抽取与放置文本行==>—— 删除并抽取文本行 ==>—— 重复与撤销操作==>——其它命令—— 全局查找——替换、替换下一个==>——回写与退出==>——执行shell命令==>// confirming substitutionThree kinds of buffers in vi:——the normal default buffer your edit file resides in——the anonymous buffer, a special buffer used for copying text ——named buffers:1-9 hold the last nine deletionsa-z for storing copied text (like the Windows clipboard) Using Buffers to Move or Copy Text5dd delete 5 lines(move cursor to some where)p put the 5 deleted lines back in a new location,below the current line2p put twiceUsing the Named Deletion Buffers"#p recover a deletion, where ＃ is the numberof the deletion you want to recover："2p the second-to-last deletion"4p the fourth from lastUsing Named Buffers"f4yy Yank four lines into buffer f.Using Search Patterns::/pattern/d Deletes the next linecontaining pattern.:g/ pattern/ Finds (moves to) the last occurrenceof pattern in the file.:g/ pattern/p Finds and displays all lines in the filecontaining pattern.:g!/ pattern/nu Finds and displays all lines in the filethat don't contain pattern;also displays line number for each line found.:60,124g/pattern/p Finds and displays any linesbetween 60 and 124 containing pattern.enter :ab SJTU Shanghai JianTong University expand:text entry mode:I study in SJTUI study in Shanghai JianTong University To disable a previous abbreviation use:unab abbreviationTo list currently defined abbreviations:ab Using Abbreviations::ab abbreviation phraseEditing multiple files:$ vi file1.txt file2.txt:e file2.txt// 5 lines yanked to buffer a // 5 lines inserted from buffer aEdit and save file1.txtEdit and save file2.txt:q "a5yy"apMove cursor ...In addition to reading the .exrc file in your home directory,many versions of vi will read a file called .exrcin the current directory. This allows you to set options that are appropriateto a particular project. (the vi configuration or startup file):set {option}displays the current value of option:set {option}={value}:set {option}:{value}Set string or number option to {value}:set shows options that either you set during theedit session or were set via your .exrc file Costomize vim using "set options":When set to "dark", Vim will try to that look good on a dark background.:set autoindent=on:set autowrite=onWrite the contents of the file, if it has been modified, on some commands :set background=light==>:set cindent=ON Enables automatic C program indenting:set fileformat=MS-Windows:set syntax=ONsyntax highlighting::syntax enable:syntax list:highlightSyntax files:The syntax and highlighting commands for one languageare normally stored in a syntax file.The name convention is: "{name}.vim". Where {name} is the nameof the language, or an abbreviation (to fit the name in 8.3 characters, a requirement in case the file is used on a DOS filesystem).Examples:c.vim perl.vim java.vim html.vimcpp.vim sh.vim csh.vim20(no space)shell script6.Extending and Managing Your Environment >>shell variables Shell variables (local)作用：—— 保存字符串—— 定制用户的工作环境—— 传递参数==>设置：my_val=20declare my_val=20查看：echo $my_val set declare ==>......清除：unset val设置变量的其它方式：my_val=20your_val=${my_val:? my_val is empty} echo $your_val my__val=20your_val=${my_val:? my_val is empty} echo $your_valUsing shell variables:path=/bash: path: readonly variable结合变量值firstname="Thomas "surname=Williammy_name=$firstname$surname 使用变量来保存系统命令参数source=/etc/passwddest=/tmp/passwd.bakcp $source $dest设置只读变量path=/usr/binreadonly path>> shell variables is local变量替换操作first="Thomas "surname=Williammy_name=$first$surnameecho This is $my_nameecho This is "$my_name"echo This is '$my_name'This is Thomas WilliamThis is Thomas WilliamThis is $my_name >>>>>>Using Quoting Correctly:This is Thomas William.This is $my_name.error message This is Thomas William.Hello,this is Thomas William.Hello,this is $my_namefirst="Thomas "surname=Williammy_name=$first$surnamecho This is $my_name.echo 'This is $my_name.'echo "This is $my_name."hello=Hello,this is $my_name.hello="Hello,this is $my_name."echo $hellohello='Hello,this is $my_name.'echo $hello echo cat hello.c >> temp echo "cat hello.c >> temp"echo `cat hello.c >> temp`"cat hello.c" to file temp cat hello.c >> temp copy hello.c to file temp双引号忽略除字符$、`、\外的其他任何字符的特殊含义反斜线屏蔽单个字符的特殊含义（& * + ^ $ ` " | ?）echo "This is 2 dollar:\$2"单引号shell会忽略任何字符的特殊含义反引号引用 shell 命令echo `ls -l`v1=3v1=`expr $v1 + 1`>> Bash Environment VariablesVariable Name Meaning————————————————————————————————_ (underscore) The last argument to the previous command.BASH Expands to the full pathname used to invoke this instance of bash.BASH_ENV Same as ENV but set only in bash versions 2.0 or above.[a]BASH_VERSINFO Version information about this version of bash if the version is 2.0 or abov BASH_VERSION Expands to the version number of this instance of bash.CDPATH The search path for the cd command.This is a colon-separated list of directories in whichthe shell looks for destination directories specified by the cd command.A sample value is .:~:/usr.COLUMNS If set, defines the width of the edit window for shell edit modes and the se DIRSTACK The current contents of the directory stack if the bash version is 2.0 or ab EDITOR Pathname for a built-in editor: emacs, gmacs, or vi.7. 几个有用的 shell 工具>>grep commandsearch a file for lines containing a given patterngrep [options] PATTERN [FILE…]cat datafile================================================northwest NW Charles Main 3.0 .98 3 34western WE Sharon Gray 5.3 .97 5 23southwest SW Lewis Dalsass 2.7 .8 2 18southern SO Suan Chin 5.1 .95 4 15southeast SE Patricia Hemenway 4.0 .7 4 17eastern EA TB Savage 4.4 .84 5 20northeast NE AM Main Jr. 5.1 .94 3 13north NO Margot Weber 4.5 .89 5 9central CT Ann Stephens 5.7 .94 5 13grep NW datafile================================================northwest NW Charles Main 3.0 .98 3 34grep 的选项:-c 只输出匹配行的计数-i 不区分大小写-h 查询多文件时不显示文件名-l 查询多文件时只输出包含匹配字符的文件名-n 显示匹配行及行号-s 不显示不存在或无匹配文本的错误信息-v 显示不包含匹配文本的所有行-E 使用扩展的正则表达式......grep '^#include' myfile.cls -l | grep '^d'grep -i may text.txtgrep -l "main" *.cgrep $string *.c *.cfind files meeting a given conditionoptions :-name 按照文件名查找文件-perm 按照文件权限来查找文件-user 按照文件属主来查找文件-group 按照文件所属的组来查找文件-mtime -n +n 按照文件的更改时间来查找文件，-type 查找某一类型的文件，-size n[c] 查找文件长度为n块的文件，带有c时表示文件长度以字节计-depth 在查找文件时，首先查找当前目录中的文件，>>find command find [-H] [-L] [-P] pathname -options [-print -exec -ok]-H Do not follow symbolic links,except while processing the command line arguments.-L Follow symbolic links.-P Never follow symbolic links.$ find /etc -type d -print$ find . -name "*.txt" –print||\/the group of operators tells findwhat action to take when it locates a fil$ find . -perm 755 -print$ find /etc -type d -print$ find / -name "CON.FILE" -depth -print$ find logs -type f -mtime +5 -exec ls -l {} \;$ find . -print >>operator1 -a operator2Find files that match both operator1 and operator2operator1 -o operator2Find files that match either operator1 or operator2.! operatorFind all files that do not match the given operator.==>to print the names of all the files in the directory and all subdirectories>>Other useful tool：df Shows the amount of free disk space (in 1K blocks) on each mounted filesystem.du Shows the amount of disk space (in 1K blocks)used by the working directory and its subdirectories. ps process infomationkill send a signal to a process to kill itkill 926uptime Shows the current time, the amount of time logged in, the number of users logged inbg put suspended process into backgroundfg bring process into foregroundmount mount the specified device at the specified mount point mount -t msdos /dev/afd0s4 /zipunmount。
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