say "Input your fineName whitch you want to extract in:"; chomp($_ = ); $_ = changePath($_); #$_ = "C:/Perl/test/5_1/2.txt"; open LOG, ">>", $_; or die "I can't create it."; my $persion; my $lines; say "From first or last?(F/L)"; while(chomp($_ = )) { $persion = $_; if($persion eq "F") { last; elsif($persion eq "L") { last; say "warn param, please again."; say "How many lines?(Please input a number)"; while(chomp($_ = )) { if(/^/d+$/) { $lines = $_; last; say "warn param, please again."; #待读取的文件名 say "The file name:"; chomp

现有一超大.sql文件,将文件前N行或后N行输入到指定文件中:  #!perl -w#将指定文件中的前N行或后N行输入到指定文件中use 5.10.1;#输出文件的名称say "Input your fineName whitch you want to extract in:";chomp($_ = );$_ = changePath($_);
集合了 所有的 Unix命令大全 登陆服务器时 输入 公帐号 openlab-open123 telnet 192.168.0.23 自己帐号 sd08077-you0 ftp工具 192.168.0.202 tools-toolss 老师测评网址 http://172.16.0.198:8080/poll/ 各个 shell 可互相切换 ksh:$ sh:$ csh:guangzhou% bash:bash-3.00$ 一、注意事项 命令和参数之间必需用空格隔开,参数和参数之间也必需用空格隔开。 一 不能超过256个字符;大小写有区分。 二、特殊字符含义 文件 名以“.”开头的都是隐藏 文件 /目录,只需在 文件 /目录名 加“.”就可隐藏它。 ~/ 表示主目录。 ./ 当 目录(一个点)。 ../ 上一级目录(两个点)。 ; 多个命令一起用。 > >> 输出重定向 。将一个命令的输出内容写入到一个 文件 里面。如果该 文件 存在, 就将该 文件 的内容覆盖; 如果不存在就先创建该 文件 , 然后再写入内容。 输出重定向,意思就是说,将原来屏幕输出变为 文件 输出,即将内容输到 文件 。 < << 输入 重定向。 本来命令是通过键盘得到 输入 的,但是用小于号,就能够使命令从 文件 得到 输入 。 \ 表示未写完,回车换 再继续。 * 匹配零个或者多个字符。 ? 匹配一个字符。 [] 匹配 括号里的内容[a-z][A-Z][0-9]。 ! 事件。 $ 取环境变量的值。 | 管道。把 一命令的输出作为后一命令的 输入 ,把几个命令连接起来。 |经常跟tee连用,tee 把内容保存到文档并显示出来。 三、通用后接命令符 -a 所有(all)。 -e 所有(every),比a更详细。 -f 取消保护。 -i 添加提示。 -p 强制执 。 -r 目录管理。 分屏显示的 途操作 空格<space> 继续打开下一屏; 回车<return> 继续打开下一 ; b 另外开上一屏; f 另外开下一屏; h 帮助; q或Ctrl+C 退出; /字符串 从上往下查找匹配的字符串; ?字符串 从下往上查找匹配的字符串; n 继续查找。 四、退出命令 exit 退出; DOS内部命令 用于退出当 的命令处理器(COMMAND.COM) 恢复 一个命令处理器。 Ctrl+d 跟exit一样效果,表 止本次操作。 logout 当csh时可用来退出,其他shell不可用。 clear 清屏,清除(之 的内容并未删除,只是没看到,拉回上面可以看回)。 五、目录管理命令 pwd 显示当 所在目录,打印当 目录的绝对路径。 cd 进入某目录,DOS内部命令 显示或改变当 目录。 cd回车/cd ~ 都是回到自己的主目录。 cd . 当 目录(空格再加一个点)。 cd .. 回到上一级目录(空格再加两个点)。 cd ../.. 向上两级。 cd /user/s0807 从绝对路径去到某目录。 cd ~/s0807 直接进入主目录下的某目录(“cd ~"相当于主目录的路径的简写)。 ls 显示当 目录的所有目录和 文件 。 用法 ls [-aAbcCdeEfFghHilLmnopqrRstux1@] [ file ...] ls /etc/ 显示某目录下的所有 文件 和目录,如etc目录下的。 ls -l (list)列表显示 文件 (默认按 文件 名排序), 显示 文件 的权限、硬链接数(即包含 文件 数,普通 文件 是1,目录1+)、用户、组名、大小、修改日期、 文件 名。 ls -t (time)按修改时间排序,显示目录和 文件 。 ls -lt 是“-l”和“-t”的组合,按时间顺序显示列表。 ls -F 显示 文件 类型,目录“/ ”结尾;可执 文件 “*”结尾;文本 文件 (none),没有结尾。 ls -R 递归显示目录结构。即该目录下的 文件 和各个副目录下的 文件 都一一显示。 ls -a 显示所有 文件 ,包括隐藏 文件 文件 权限 r 读权限。对普通 文件 来说,是读取该 文件 的权限;对目录来说,是获得该目录下的 文件 信息。 w 写权限。对 文件 ,是修改;对目录,是增删 文件 与子目录。 (注 删除没有写权限的 文件 可以用 rm -f ,这是为了操作方便,是人性化的设计)。 x 执 权限;对目录,是进入该目录 - 表示没有权限 形式 - rw- r-- r-- 其 第一个是 文件 类型(-表普通 文件 ,d表目录,l表软链接 文件 ) 第2~4个是属主,生成 文件 时登录的人,权限最高,用u表示 第5~7个是属组,系统管理员分配的同组的一个或几个人,用g表示 第8~10个是其他人,除属组外的人,用o表示 所有人,包括属主、属组及其他人,用a表示 chmod 更改权限; 用法 chmod [-fR] <绝对模式> 文件 ... chmod [-fR] <符号模式列表> 文件 ... 其 <符号模式列表> 是一个用逗号分隔的表 [ugoa]{+|-|=}[rwxXlstugo] chmod u+rw 给用户加权限。同理,u-rw也可以减权限。 chmod u=rw 给用户赋权限。与加权限不一样,赋权限有覆盖的效果。 主要形式有如下几种 chmod u+rw chmod u=rw chmod u+r, u+w chmod u+rw,g+w, o+r chmod 777( 用数字的方式设置权限是最常用的) 数字表示权限时,各数位分别表示属主、属组及其他人; 其 ,1是执 权(Execute),2是写权限(Write),4是读权限(Read), 具体权限相当于三种权限的数相加,如7=1+2+4,即拥有读写和执 权。 另外,临时 文件 /目录的权限为rwt,可写却不可删,关机后自动删除;建临时目录:chmod 777 目录名,再chmod +t 目录名。 id 显示用户有效的uid(用户字)和gid(组名) 用法 id [-ap] [user] id 显示自己的。 id root 显示root的。 id -a root 显示用户所在组的所有组名(如root用户,是所有组的组员) df 查看 文件 系统,查看数据区 用法 df [-F FSType] [-abeghklntVvZ] [-o FSType 特定选项] [目录 | 块设备 | 资源] df -k 以kbytes显示 文件 大小的查看 文件 系统方式 六、显示 文件 内容 more 分屏显示 文件 的内容。 用法 more [-cdflrsuw] [- ] [+ 号] [+/模式] [ 文件 名 ...]。 显示7个信息:用户名 密码 用户id(uid) 组id(gid) 描述信息(一般为空) 用户主目录 login shell(登录shell) cat 显示 文件 内容,不分屏(一般用在小 文件 ,大 文件 显示不下);合并 文件 ,仅在屏幕上合并,并不改变原 文件 。 用法 cat [ -usvtebn ] [-| 文件 ] ... tail 实时监控 文件 ,一般用在日志 文件 ,可以只看其 几行 。 用法 tail [+/-[n][lbc][f]] [ 文件 ] tail [+/-[n][l][r|f]] [ 文件 ] 七、 文件 /目录的增删 echo 显示一 内容。 touch 如果 文件 /目录不存在,则创建新 文件 /目录;如果 文件 存在,那么就是更新该 文件 的最后访问时间, 用法 touch [-acm] [-r ref_ file ] 文件 ... touch [-acm] [MMDDhhmm[yy]] 文件 ... touch [-acm] [-t [[CC]YY]MMDDhhmm[.SS]] file ... mkdir 创建目录(必须有创建目录的权限) 用法 mkdir [-m 模式] [-p] dirname ... mkdir dir1/dir2 在dir1下建dir2 mkdir dir13 dir4 dir5 连建多个 mkdir ~/games 用户主目录下建(默认在当 目录下创建) mkdir -p dir6/dir7/dir8 强制创建dir8;若没有 面的目录,会自动创建dir6和dir7。 不用-p时,若没有dir6/dir7,则创建失败。 cp 复制 文件 /目录 cp 源 文件 目标 文件 复制 文件 ;若已有 文件 则覆盖 cp -r 源目录 目标目录 复制目录;若已有目录则把源目录复制到目标目录下, 没有目标目录时,相当于完全复制源目录,只是 文件 名不同。 cp beans apple dir2 把beans、apple 文件 复制到dir2目录下 cp -i beans apple 增加是否覆盖的提示 mv 移动或重命名 文件 /目录 用法 mv [-f] [-i] f1 f2 mv [-f] [-i] f1 ... fn d1 mv [-f] [-i] d1 d2 mv 源 文件 名 目标 文件 名 若目标 文件 名还没有,则是源 文件 重命名为目标 文件 ;若目标 文件 已存在,则源 文件 覆盖目标 文件 。 mv 源 文件 名 目标目录 移动 文件 mv 源目录 目标目录 若目标目录不存在,则源目录重命名;若目标目录已存在,则源目录移动到目标目录下。 rm 删除 文件 /目录 用法 rm [-fiRr] 文件 ... rm 文件 名 删除 文件 。 rm -r 目录名 删除目录。 rm –f 文件 只要是该 文件 或者目录的拥有者,无论是否有权限删除,都可以用这个命令参数强 删除。 rm -rf * 删除所有 文件 及目录 rmdir 删除空目录。只可以删除空目录。 ln 创建硬链接或软链接,硬链接=同一 文件 的多个名字;软链接=快捷方式 用法 ln [-f] [-n] [-s] f1 [f2] ln [-f] [-n] [-s] f1 ... fn d1 ln [-f] [-n] -s d1 d2 ln file 1 file 1.ln 创建硬链接。感觉是同一 文件 ,删除一个,对另一个没有影响;须两个都删除才算删除。 ln -s file 1 file 1.sln 创建软链接。可跨系统操作,冲破操作权限;也是快捷方式。 八、时间显示 date 显示时间,精确到秒 用法 date [-u] mmddHHMM[[cc]yy][.SS] date [-u] [+format] date -a [-]sss[.fff] cal 显示日历 cal 9 2008 显示2008年9月的日历; cal 显示当月的 用法 cal [ [月] 年 ] man 帮助( format and display the on-line manual pages) 用法 man [-] [-adFlrt] [-M 路径] [-T 宏软件包] [-s 段] 名称 ... man [-] [-adFlrt] [-M path] [-T macro-package] [-s section] name... man [-M 路径] -k 关键字 ... man [-M 路径] -f 文件 ... awk 按一定格式输出(pattern scanning and processing language) 用法 awk [-Fc] [-f 源代码 | 'cmds'] [ 文件 ] 底 模式 /? 命令模式 i a o 输入 模式 vi 的使用方法 1、光标 h 左 j 下 k 上 l 右 set nu 显示 号(set nonu) 21 光标停在 指定 21G 第N (G到 文件 尾,1G到 文件 头) 如果要将光标移动到 文件 第一 ,那么就按 1G H 屏幕头 M 屏幕 间 L 屏幕底 ^ 或 shift+6 首 $ 或 shift+4 尾 Ctrl+f 下翻 Ctrl+b 上翻 2、 输入 ( 输入 模式) o 光标往下换一 O (大写字母o)在光标所在 上插入一空 i 在光标所在位置的 面插入字母 a 在光标所在位置的后面插入一个新字母 <Esc> 退出插入状态。 3、修改替换 r 替换一个字符 dd 删除 ,剪切 (5dd删除5 ) 5,10d 删除 5 至 10 (包括第 5 和第 10 ) x 删除一个字符 dw 删除词,剪切词。 ( 3dw删除 3 单词) cw 替换一个单词。 (cw 和 dw 的区别 cw 删除某一个单词后直接进入编辑模式,而dw删除词后仍处于命令模式) cc 替换一 C 替换从光标到 尾 yy 复制 (用法同下的 Y ,见下 ) Y 将光标移动到要复制 位置,按yy。当你想粘贴的时候,请将光标移动到你想复制的位置的 一个位置,然后按 p yw 复制词 p 当 下粘贴 1,2co3 复制 1,2在 3之后 4,5m6 移动 4,5在 6之后 u 当你的 一个命令操作是一个误操作的时候,那么可以按一下 u键,即可复原。只能撤销一次 r file 2 在光标所在处插入另一个 文件 ~ 将字母变成大写 J 可以将当 与下一 连接起来 /字符串 从上往下找匹配的字符串 ?字符串 从下往上找匹配的字符串 n 继续查找 1,$s/旧串/新串/g 替换全文(或者 %s/旧串/新串/g) (1表示从第一 开始) 没有g则只替换一次,加g替换所有 3、存盘和退出 w 存盘 w new file 存成新 文件 wq 存盘再退出VI(或者ZZ或 X) q! 强 退出不存盘 users 显示在线用户(仅显示用户名)。 who 显示在线用户,但比users更详细,包括用户名、终端号、登录时间、IP地址。 who am i 仅显示自己,(但包括用户名、端口、登录时间、IP地址;信息量=who)。 whoami 也仅显示自己,但只有用户名(仅显示自己的有效的用户名)。 w 显示比who更多内容,还包括闲置时间、占CPU、平均占用CPU、执 命令。 用法 w [ -hlsuw ] [ 用户 ] su 改变用户,需再 输入 密码。 用法 su [-] [ username [ arg ... ] ] su - 相当于退出再重新登录。 find 查找 文件 用法 find [-H | -L] 路径列表 谓词列表 find / -name perl 从根目录开始查找名为 perl 文件 。 find . -mtime 10 -print 从当 目录查找距离现在10天时修改的 文件 ,显示在屏幕上。 (注 “10”表示第10天的时候;如果是“+10”表示10天以外的范围;“-10”表示10天以内的范围。) grep 文件 查找字符;有过滤功能,只列出想要的内容 用法 grep -hblcnsviw 模式 文件 . . . 如 grep abc /etc/passwd 在passwd 文件 下找abc字符 wc 统计 -l 统计 数; -w统计单词数; -c 统计字符数 如 grep wang /etc/passwd|wc -l 统计passwd 文件 含“wang”的 数 du 查看目录情况 如 du -sk * 不加-s会显示子目录,-k按千字节排序 用法 du [-a] [-d] [-h|-k] [-r] [-o|-s] [-H|-L] [ 文件 ...] ps 显示进程。 用法 ps [ -aAdeflcjLPyZ ] [ -o 格式 ] [ -t 项列表 ] [ -u 用户列表 ] [ -U 用户列表 ] [ -G 组列表 ] [ -p 进程列表 ] [ -g 程序组列表 ] [ -s 标识符列表 ] [ -z 区域列表 ] ps 显示自己的进程。 ps -e 显示每个进程,包括空闲进程。 ps -f 显示详情。 ps -ef 组合-e和-f,所有进程的详情。 ps -U uidlist(用户列表) 具体查看某人的进程。 pkill sleep 用法 jobs [-l ] fg %n bg %n stop %n 挂起(仅csh能用) Ctrl+C Ctrl+Z usage ping host [timeout] usage ping -s [-l | U] [adLnRrv] [-A addr_family] [-c traffic_class] [-g gateway [-g gateway ...]] [-F flow_label] [-I interval] [-i interface] [-P tos] [-p port] [-t ttl] host [data_size] [npackets] ifconfig -a /sbin/ifconfig 查看本机的IP地址 netstat -rn rlogin 帮助 文件 [sd0807@localhost ~]$ help GNU bash, version 3.1.17(1)-release (i686-redhat-linux-gnu) These shell commands are defined internally. Type `help' to see this list. Type `help name' to find out more about the function `name'. Use `info bash' to find out more about the shell in general. Use `man -k' or `info' to find out more about commands not in this list. A star (*) next to a name means that the command is disabled. JOB_SPEC [&] (( expression )) . file name [arguments] [ arg... ] [[ expression ]] alias [-p] [name[=value] ... ] bg [job_spec ...] bind [-lpvsPVS] [-m keymap] [-f fi break [n] builtin [shell-builtin [arg ...]] caller [EXPR] case WORD in [PATTERN [| PATTERN]. cd [-L|-P] [dir] command [-pVv] command [arg ...] compgen [-abcdefgjksuv] [-o option complete [-abcdefgjksuv] [-pr] [-o continue [n] declare [-afFirtx] [-p] [name[=val dirs [-clpv] [+N] [-N] disown [-h] [-ar] [jobspec ...] echo [-neE] [arg ...] enable [-pnds] [-a] [-f file name] eval [arg ...] exec [-cl] [-a name] file [redirec exit [n] export [-nf] [name[=value] ...] or false fc [-e ename] [-nlr] [first] [last fg [job_spec] for NAME [in WORDS ... ;] do COMMA for (( exp1; exp2; exp3 )); do COM function NAME { COMMANDS ; } or NA getopts optstring name [arg] hash [-lr] [-p pathname] [-dt] [na help [-s] [pattern ...] history [-c] [-d offset] [n] or hi if COMMANDS; then COMMANDS; [ elif jobs [-lnprs] [jobspec ...] or job kill [-s sigspec | -n signum | -si let arg [arg ...] local name[=value] ... logout popd [+N | -N] [-n] printf [-v var] format [arguments] pushd [dir | +N | -N] [-n] pwd [-LP] read [-ers] [-u fd] [-t timeout] [ readonly [-af] [name[=value] ...] return [n] select NAME [in WORDS ... ;] do CO set [--abefhkmnptuvxBCHP] [-o option] [arg ...] shift [n] shopt [-pqsu] [-o long-option] opt source file name [arguments] suspend [-f] test [expr] time [-p] PIPELINE times trap [-lp] [arg signal_spec ...] true type [-afptP] name [name ...] typeset [-afFirtx] [-p] name[=valu ulimit [-SHacdfilmnpqstuvx] [limit umask [-p] [-S] [mode] unalias [-a] name [name ...] unset [-f] [-v] [name ...] until COMMANDS; do COMMANDS; done variables - Some variable names an wait [n] while COMMANDS; do COMMANDS; done { COMMANDS ; } 输入 man help BASH_BUILTINS(1) BASH_BUILTINS(1) bash, :, ., [, alias, bg, bind, break, builtin, cd, command, compgen, complete, continue, declare, dirs, disown, echo, enable, eval, exec, exit, export, fc, fg, getopts, hash, help, history, jobs, kill, let, local, logout, popd, printf, pushd, pwd, read, readonly, return, set, shift, shopt, source, suspend, test, times, trap, type, typeset, ulimit, umask, una- lias, unset, wait - bash built-in commands, see bash(1) BASH BUILTIN COMMANDS Unless otherwise noted, each builtin command documented in this section as accepting options preceded by - accepts -- to signify the end of the options. For example, the :, true, false, and test builtins do not accept options. : [arguments] No effect; the command does nothing beyond expanding arguments and performing any specified redirections. A zero exit code is returned. . file name [arguments] source file name [arguments] Read and execute commands from file name in the current shell environment and return the exit status of the last command executed from file name. If file name does not contain a slash, file names in PATH are used to find the directory containing file - name. The file searched for in PATH need not be executable. When bash is not in posix mode, the current directory is searched if no file is found in PATH. If the sourcepath option to the shopt builtin command is turned off, the PATH is not searched. If any arguments are supplied, they become the positional parameters when file name is executed. Otherwise the positional parameters are unchanged. The return status is the status of the last command exited within the script (0 if no commands are executed), and false if file name is not found or cannot be read. alias [-p] [name[=value] ...] Alias with no arguments or with the -p option prints the list of aliases in the form alias name=value on standard output. When arguments are supplied, an alias is defined for each name whose value is given. A trailing space in value causes the next word to be checked for alias substitution when the alias is expanded. For each name in the argument list for which no value is supplied, the name and value of the alias is printed. Alias returns true unless a name is given for which no alias has been defined. bg [jobspec ...] Resume each suspended job jobspec in the background, as if it had been started with &. If jobspec is not present, the shell’s notion of the current job is used. bg jobspec returns 0 unless run when job control is disabled or, when run with job con- trol enabled, any specified jobspec was not found or was started without job control. bind [-m keymap] [-lpsvPSV] bind [-m keymap] [-q function] [-u function] [-r keyseq] bind [-m keymap] -f file name bind [-m keymap] -x keyseq:shell-command bind [-m keymap] keyseq:function-name bind readline-command Display current readline key and function bindings, bind a key sequence to a readline function or macro, or set a readline variable. Each non-option argument is a command as it would appear in . input rc, but each binding or command must be passed as a sepa- rate argument; e.g., ’"\C-x\C-r": re-read-init- file ’. Options, if supplied, have the following meanings: -m keymap Use keymap as the keymap to be affected by the subsequent bindings. Accept- able keymap names are emacs, emacs-standard, emacs-meta, emacs-ctlx, vi, vi-move, vi-command, and vi-insert. vi is equivalent to vi-command; emacs is equivalent to emacs-standard. -l List the names of all readline functions. -p Display readline function names and bindings in such a way that they can be re-read. -P List current readline function names and bindings. -v Display readline variable names and values in such a way that they can be re- read. -V List current readline variable names and values. -s Display readline key sequences bound to macros and the strings they output in such a way that they can be re-read. -S Display readline key sequences bound to macros and the strings they output. -f file name Read key bindings from file name. -q function Query about which keys invoke the named function. -u function Unbind all keys bound to the named function. -r keyseq Remove any current binding for keyseq. -x keyseq:shell-command Cause shell-command to be executed whenever keyseq is entered. The return value is 0 unless an unrecognized option is given or an error occurred. break [n] Exit from within a for, while, until, or select loop. If n is specified, break n levels. n must be ≥ 1. If n is greater than the number of enclosing loops, all enclosing loops are exited. The return value is 0 unless the shell is not executing a loop when break is executed. builtin shell-builtin [arguments] Execute the specified shell builtin, passing it arguments, and return its exit sta- tus. This is useful when defining a function whose name is the same as a shell builtin, retaining the functionality of the builtin within the function. The cd builtin is commonly redefined this way. The return status is false if shell-builtin is not a shell builtin command. cd [-L|-P] [dir] Change the current directory to dir. The variable HOME is the default dir. The variable CDPATH defines the search path for the directory containing dir. Alterna- tive directory names in CDPATH are separated by a colon (:). A null directory name in CDPATH is the same as the current directory, i.e., ‘‘.’’. If dir begins with a slash (/), then CDPATH is not used. The -P option says to use the physical directory structure instead of following symbolic links (see also the -P option to the set builtin command); the -L option forces symbolic links to be followed. An argument of - is equivalent to $OLDPWD. If a non-empty directory name from CDPATH is used, or if - is the first argument, and the directory change is successful, the absolute path- name of the new working directory is written to the standard output. The return value is true if the directory was successfully changed; false otherwise. caller [expr] Returns the context of any active subroutine call (a shell function or a script exe- cuted with the . or source builtins. Without expr, caller displays the line number and source file name of the current subroutine call. If a non-negative integer is supplied as expr, caller displays the line number, subroutine name, and source file corresponding to that position in the current execution call stack. This extra information may be used, for example, to print a stack trace. The current frame is frame 0. The return value is 0 unless the shell is not executing a subroutine call or expr does not correspond to a valid position in the call stack. command [-pVv] command [arg ...] Run command with args suppressing the normal shell function lookup. Only builtin com- mands or commands found in the PATH are executed. If the -p option is given, the search for command is performed using a default value for PATH that is guaranteed to find all of the standard utilities. If either the -V or -v option is supplied, a description of command is printed. The -v option causes a single word indicating the command or file name used to invoke command to be displayed; the -V option produces a more verbose description. If the -V or -v option is supplied, the exit status is 0 if command was found, and 1 if not. If neither option is supplied and an error occurred or command cannot be found, the exit status is 127. Otherwise, the exit status of the command builtin is the exit status of command. compgen [option] [word] Generate possible completion matches for word according to the options, which may be any option accepted by the complete builtin with the exception of -p and -r, and write the matches to the standard output. When using the -F or -C options, the vari- ous shell variables set by the programmable completion facilities, while available, will not have useful values. The matches will be generated in the same way as if the programmable completion code had generated them directly from a completion specification with the same flags. If word is specified, only those completions matching word will be displayed. The return value is true unless an invalid option is supplied, or no matches were generated. complete [-abcdefgjksuv] [-o comp-option] [-A action] [-G globpat] [-W wordlist] [-P prefix] [-S suffix] [-X filterpat] [-F function] [-C command] name [name ...] complete -pr [name ...] Specify how arguments to each name should be completed. If the -p option is sup- plied, or if no options are supplied, existing completion specifications are printed in a way that allows them to be reused as input . The -r option removes a completion specification for each name, or, if no names are supplied, all completion specifica- tions. The process of applying these completion specifications when word completion is attempted is described above under Programmable Completion. Other options, if specified, have the following meanings. The arguments to the -G, -W, and -X options (and, if necessary, the -P and -S options) should be quoted to protect them from expansion before the complete builtin is invoked. -o comp-option The comp-option controls several aspects of the compspec’s behavior beyond the simple generation of completions. comp-option may be one of: bashdefault Perform the rest of the default bash completions if the compspec gen- erates no matches. default Use readline’s default file name completion if the compspec generates no matches. dirnames Perform directory name completion if the compspec generates no matches. file names Tell readline that the compspec generates file names, so it can per- form any file name-specific processing (like adding a slash to direc- tory names or suppressing trailing spaces). Intended to be used with shell functions. nospace Tell readline not to append a space (the default) to words completed at the end of the line. plusdirs After any matches defined by the compspec are generated, directory name completion is attempted and any matches are added to the results of the other actions. -A action The action may be one of the following to generate a list of possible comple- tions: alias Alias names. May also be specified as -a. arrayvar Array variable names. binding Readline key binding names. builtin Names of shell builtin commands. May also be specified as -b. command Command names. May also be specified as -c. directory Directory names. May also be specified as -d. disabled Names of disabled shell builtins. enabled Names of enabled shell builtins. export Names of exported shell variables. May also be specified as -e. file File names. May also be specified as -f. function Names of shell functions. group Group names. May also be specified as -g. helptopic Help topics as accepted by the help builtin. hostname Hostnames, as taken from the file specified by the HOST FILE shell variable. job Job names, if job control is active. May also be specified as -j. keyword Shell reserved words. May also be specified as -k. running Names of running jobs, if job control is active. service Service names. May also be specified as -s. setopt Valid arguments for the -o option to the set builtin. shopt Shell option names as accepted by the shopt builtin. signal Signal names. stopped Names of stopped jobs, if job control is active. user User names. May also be specified as -u. variable Names of all shell variables. May also be specified as -v. -G globpat The file name expansion pattern globpat is expanded to generate the possible completions. -W wordlist The wordlist is split using the characters in the IFS special variable as delimiters, and each resultant word is expanded. The possible completions are the members of the resultant list which match the word being completed. -C command command is executed in a subshell environment, and its output is used as the possible completions. -F function The shell function function is executed in the current shell environment. When it finishes, the possible completions are retrieved from the value of the COMPREPLY array variable. -X filterpat filterpat is a pattern as used for file name expansion. It is applied to the list of possible completions generated by the preceding options and argu- ments, and each completion matching filterpat is removed from the list. A leading ! in filterpat negates the pattern; in this case, any completion not matching filterpat is removed. -P prefix prefix is added at the beginning of each possible completion after all other options have been applied. -S suffix suffix is appended to each possible completion after all other options have been applied. The return value is true unless an invalid option is supplied, an option other than -p or -r is supplied without a name argument, an attempt is made to remove a comple- tion specification for a name for which no specification exists, or an error occurs adding a completion specification. continue [n] Resume the next iteration of the enclosing for, while, until, or select loop. If n is specified, resume at the nth enclosing loop. n must be ≥ 1. If n is greater than the number of enclosing loops, the last enclosing loop (the ‘‘top-level’’ loop) is resumed. The return value is 0 unless the shell is not executing a loop when con- tinue is executed. declare [-afFirtx] [-p] [name[=value] ...] typeset [-afFirtx] [-p] [name[=value] ...] Declare variables and/or give them attributes. If no names are given then display the values of variables. The -p option will display the attributes and values of each name. When -p is used, additional options are ignored. The -F option inhibits the display of function definitions; only the function name and attributes are printed. If the extdebug shell option is enabled using shopt, the source file name and line number where the function is defined are displayed as well. The -F option implies -f. The following options can be used to restrict output to variables with the specified attribute or to give variables attributes: -a Each name is an array variable (see Arrays above). -f Use function names only. -i The variable is treated as an integer; arithmetic evaluation (see ARITHMETIC EVALUATION ) is performed when the variable is assigned a value. -r Make names readonly. These names cannot then be assigned values by subsequent assignment statements or unset. -t Give each name the trace attribute. Traced functions inherit the DEBUG and RETURN traps from the calling shell. The trace attribute has no special mean- ing for variables. -x Mark names for export to subsequent commands via the environment. Using ‘+’ instead of ‘-’ turns off the attribute instead, with the exception that +a may not be used to destroy an array variable. When used in a function, makes each name local, as with the local command. If a variable name is followed by =value, the value of the variable is set to value. The return value is 0 unless an invalid option is encountered, an attempt is made to define a function using ‘‘-f foo=bar’’, an attempt is made to assign a value to a readonly variable, an attempt is made to assign a value to an array variable without using the compound assignment syntax (see Arrays above), one of the names is not a valid shell variable name, an attempt is made to turn off readonly status for a readonly variable, an attempt is made to turn off array status for an array variable, or an attempt is made to display a non-exis- tent function with -f. dirs [-clpv] [+n] [-n] Without options, displays the list of currently remembered directories. The default display is on a single line with directory names separated by spaces. Directories are added to the list with the pushd command; the popd command removes entries from the list. +n Displays the nth entry counting from the left of the list shown by dirs when invoked without options, starting with zero. -n Displays the nth entry counting from the right of the list shown by dirs when invoked without options, starting with zero. -c Clears the directory stack by deleting all of the entries. -l Produces a longer listing; the default listing format uses a tilde to denote the home directory. -p Print the directory stack with one entry per line. -v Print the directory stack with one entry per line, prefixing each entry with its index in the stack. The return value is 0 unless an invalid option is supplied or n indexes beyond the end of the directory stack. disown [-ar] [-h] [jobspec ...] Without options, each jobspec is removed from the table of active jobs. If the -h option is given, each jobspec is not removed from the table, but is marked so that SIGHUP is not sent to the job if the shell receives a SIGHUP. If no jobspec is present, and neither the -a nor the -r option is supplied, the current job is used. If no jobspec is supplied, the -a option means to remove or mark all jobs; the -r option without a jobspec argument restricts operation to running jobs. The return value is 0 unless a jobspec does not specify a valid job. echo [-neE] [arg ...] Output the args, separated by spaces, followed by a newline. The return status is always 0. If -n is specified, the trailing newline is suppressed. If the -e option is given, interpretation of the following backslash-escaped characters is enabled. The -E option disables the interpretation of these escape characters, even on systems where they are interpreted by default. The xpg_echo shell option may be used to dynamically determine whether or not echo expands these escape characters by default. echo does not interpret -- to mean the end of options. echo interprets the following escape sequences: \a alert (bell) \b backspace \c suppress trailing newline \e an escape character \f form feed \n new line \r carriage return \t horizontal tab \v vertical tab \\ backslash \0nnn the eight-bit character whose value is the octal value nnn (zero to three octal digits) \nnn the eight-bit character whose value is the octal value nnn (one to three octal digits) \xHH the eight-bit character whose value is the hexadecimal value HH (one or two hex digits) enable [-adnps] [-f file name] [name ...] Enable and disable builtin shell commands. Disabling a builtin allows a disk command which has the same name as a shell builtin to be executed without specifying a full pathname, even though the shell normally searches for builtins before disk commands. If -n is used, each name is disabled; otherwise, names are enabled. For example, to use the test binary found via the PATH instead of the shell builtin version, run ‘‘enable -n test’’. The -f option means to load the new builtin command name from shared object file name, on systems that support dynamic loading. The -d option will delete a builtin previously loaded with -f. If no name arguments are given, or if the -p option is supplied, a list of shell builtins is printed. With no other option arguments, the list consists of all enabled shell builtins. If -n is supplied, only disabled builtins are printed. If -a is supplied, the list printed includes all builtins, with an indication of whether or not each is enabled. If -s is supplied, the output is restricted to the POSIX special builtins. The return value is 0 unless a name is not a shell builtin or there is an error loading a new builtin from a shared object. eval [arg ...] The args are read and concatenated together into a single command. This command is then read and executed by the shell, and its exit status is returned as the value of eval. If there are no args, or only null arguments, eval returns 0. exec [-cl] [-a name] [command [arguments]] If command is specified, it replaces the shell. No new process is created. The arguments become the arguments to command. If the -l option is supplied, the shell places a dash at the beginning of the zeroth arg passed to command. This is what login(1) does. The -c option causes command to be executed with an empty environ- ment. If -a is supplied, the shell passes name as the zeroth argument to the exe- cuted command. If command cannot be executed for some reason, a non-interactive shell exits, unless the shell option execfail is enabled, in which case it returns failure. An interactive shell returns failure if the file cannot be executed. If command is not specified, any redirections take effect in the current shell, and the return status is 0. If there is a redirection error, the return status is 1. exit [n] Cause the shell to exit with a status of n. If n is omitted, the exit status is that of the last command executed. A trap on EXIT is executed before the shell termi- nates. export [-fn] [name[=word]] ... export -p The supplied names are marked for automatic export to the environment of subsequently executed commands. If the -f option is given, the names refer to functions. If no names are given, or if the -p option is supplied, a list of all names that are exported in this shell is printed. The -n option causes the export property to be removed from each name. If a variable name is followed by =word, the value of the variable is set to word. export returns an exit status of 0 unless an invalid option is encountered, one of the names is not a valid shell variable name, or -f is sup- plied with a name that is not a function. fc [-e ename] [-nlr] [first] [last] fc -s [pat=rep] [cmd] Fix Command. In the first form, a range of commands from first to last is selected from the history list. First and last may be specified as a string (to locate the last command beginning with that string) or as a number (an index into the history list, where a negative number is used as an offset from the current command number). If last is not specified it is set to the current command for listing (so that ‘‘fc -l -10’’ prints the last 10 commands) and to first otherwise. If first is not speci- fied it is set to the previous command for editing and -16 for listing. The -n option suppresses the command numbers when listing. The -r option reverses the order of the commands. If the -l option is given, the commands are listed on standard output. Otherwise, the editor given by ename is invoked on a file contain- ing those commands. If ename is not given, the value of the FCEDIT variable is used, and the value of EDITOR if FCEDIT is not set. If neither variable is set, is used. When editing is complete, the edited commands are echoed and executed. In the second form, command is re-executed after each instance of pat is replaced by rep. A useful alias to use with this is ‘‘r="fc -s"’’, so that typing ‘‘r cc’’ runs the last command beginning with ‘‘cc’’ and typing ‘‘r’’ re-executes the last command. If the first form is used, the return value is 0 unless an invalid option is encoun- tered or first or last specify history lines out of range. If the -e option is sup- plied, the return value is the value of the last command executed or failure if an error occurs with the temporary file of commands. If the second form is used, the return status is that of the command re-executed, unless cmd does not specify a valid history line, in which case fc returns failure. fg [jobspec] Resume jobspec in the foreground, and make it the current job. If jobspec is not present, the shell’s notion of the current job is used. The return value is that of the command placed into the foreground, or failure if run when job control is dis- abled or, when run with job control enabled, if jobspec does not specify a valid job or jobspec specifies a job that was started without job control. getopts optstring name [args] getopts is used by shell procedures to parse positional parameters. optstring con- tains the option characters to be recognized; if a character is followed by a colon, the option is expected to have an argument, which should be separated from it by white space. The colon and question mark characters may not be used as option char- acters. Each time it is invoked, getopts places the next option in the shell vari- able name, initializing name if it does not exist, and the index of the next argument to be processed into the variable OPTIND. OPTIND is initialized to 1 each time the shell or a shell script is invoked. When an option requires an argument, getopts places that argument into the variable OPTARG. The shell does not reset OPTIND auto- matically; it must be manually reset between multiple calls to getopts within the same shell invocation if a new set of parameters is to be used. When the end of options is encountered, getopts exits with a return value greater than zero. OPTIND is set to the index of the first non-option argument, and name is set to ?. getopts normally parses the positional parameters, but if more arguments are given in args, getopts parses those instead. getopts can report errors in two ways. If the first character of optstring is a colon, silent error reporting is used. In normal operation diagnostic messages are printed when invalid options or missing option arguments are encountered. If the variable OPTERR is set to 0, no error messages will be displayed, even if the first character of optstring is not a colon. If an invalid option is seen, getopts places ? into name and, if not silent, prints an error message and unsets OPTARG. If getopts is silent, the option character found is placed in OPTARG and no diagnostic message is printed. If a required argument is not found, and getopts is not silent, a question mark (?) is placed in name, OPTARG is unset, and a diagnostic message is printed. If getopts is silent, then a colon (:) is placed in name and OPTARG is set to the option charac- ter found. getopts returns true if an option, specified or unspecified, is found. It returns false if the end of options is encountered or an error occurs. hash [-lr] [-p file name] [-dt] [name] For each name, the full file name of the command is determined by searching the directories in $PATH and remembered. If the -p option is supplied, no path search is performed, and file name is used as the full file name of the command. The -r option causes the shell to forget all remembered locations. The -d option causes the shell to forget the remembered location of each name. If the -t option is supplied, the full pathname to which each name corresponds is printed. If multiple name arguments are supplied with -t, the name is printed before the hashed full pathname. The -l option causes output to be displayed in a format that may be reused as input . If no arguments are given, or if only -l is supplied, information about remembered commands is printed. The return status is true unless a name is not found or an invalid option is supplied. help [-s] [pattern] Display helpful information about builtin commands. If pattern is specified, help gives detailed help on all commands matching pattern; otherwise help for all the builtins and shell control structures is printed. The -s option restricts the infor- mation displayed to a short usage synopsis. The return status is 0 unless no command matches pattern. history [n] history -c history -d offset history -anrw [ file name] history -p arg [arg ...] history -s arg [arg ...] With no options, display the command history list with line numbers. Lines listed with a * have been modified. An argument of n lists only the last n lines. If the shell variable HISTTIMEFORMAT is set and not null, it is used as a format string for strftime(3) to display the time stamp associated with each displayed history entry. No intervening blank is printed between the formatted time stamp and the history line. If file name is supplied, it is used as the name of the history file ; if not, the value of HIST FILE is used. Options, if supplied, have the following meanings: -c Clear the history list by deleting all the entries. -d offset Delete the history entry at position offset. -a Append the ‘‘new’’ history lines (history lines entered since the beginning of the current bash session) to the history file . -n Read the history lines not already read from the history file into the current history list. These are lines appended to the history file since the begin- ning of the current bash session. -r Read the contents of the history file and use them as the current history. -w Write the current history to the history file , overwriting the history file ’s contents. -p Perform history substitution on the following args and display the result on the standard output. Does not store the results in the history list. Each arg must be quoted to disable normal history expansion. -s Store the args in the history list as a single entry. The last command in the history list is removed before the args are added. If the HISTTIMEFORMAT is set, the time stamp information associated with each history entry is written to the history file . The return value is 0 unless an invalid option is encountered, an error occurs while reading or writing the history file , an invalid offset is supplied as an argument to -d, or the history expansion supplied as an argument to -p fails. jobs [-lnprs] [ jobspec ... ] jobs -x command [ args ... ] The first form lists the active jobs. The options have the following meanings: -l List process IDs in addition to the normal information. -p List only the process ID of the job’s process group leader. -n Display information only about jobs that have changed status since the user was last notified of their status. -r Restrict output to running jobs. -s Restrict output to stopped jobs. If jobspec is given, output is restricted to information about that job. The return status is 0 unless an invalid option is encountered or an invalid jobspec is sup- plied. If the -x option is supplied, jobs replaces any jobspec found in command or args with the corresponding process group ID, and executes command passing it args, returning its exit status. kill [-s sigspec | -n signum | -sigspec] [pid | jobspec] ... kill -l [sigspec | exit_status] Send the signal named by sigspec or signum to the processes named by pid or jobspec. sigspec is either a case-insensitive signal name such as SIGKILL (with or without the SIG prefix) or a signal number; signum is a signal number. If sigspec is not present, then SIGTERM is assumed. An argument of -l lists the signal names. If any arguments are supplied when -l is given, the names of the signals corresponding to the arguments are listed, and the return status is 0. The exit_status argument to -l is a number specifying either a signal number or the exit status of a process termi- nated by a signal. kill returns true if at least one signal was successfully sent, or false if an error occurs or an invalid option is encountered. let arg [arg ...] Each arg is an arithmetic expression to be evaluated (see ARITHMETIC EVALUATION). If the last arg evaluates to 0, let returns 1; 0 is returned otherwise. local [option] [name[=value] ...] For each argument, a local variable named name is created, and assigned value. The option can be any of the options accepted by declare. When local is used within a function, it causes the variable name to have a visible scope restricted to that function and its children. With no operands, local writes a list of local variables to the standard output. It is an error to use local when not within a function. The return status is 0 unless local is used outside a function, an invalid name is sup- plied, or name is a readonly variable. logout Exit a login shell. popd [-n] [+n] [-n] Removes entries from the directory stack. With no arguments, removes the top direc- tory from the stack, and performs a cd to the new top directory. Arguments, if sup- plied, have the following meanings: +n Removes the nth entry counting from the left of the list shown by dirs, start- ing with zero. For example: ‘‘popd +0’’ removes the first directory, ‘‘popd +1’’ the second. -n Removes the nth entry counting from the right of the list shown by dirs, starting with zero. For example: ‘‘popd -0’’ removes the last directory, ‘‘popd -1’’ the next to last. -n Suppresses the normal change of directory when removing directories from the stack, so that only the stack is manipulated. If the popd command is successful, a dirs is performed as well, and the return status is 0. popd returns false if an invalid option is encountered, the directory stack is empty, a non-existent directory stack entry is specified, or the directory change fails. printf [-v var] format [arguments] Write the formatted arguments to the standard output under the control of the format. The format is a character string which contains three types of objects: plain charac- ters, which are simply copied to standard output, character escape sequences, which are converted and copied to the standard output, and format specifications, each of which causes printing of the next successive argument. In addition to the standard printf(1) formats, %b causes printf to expand backslash escape sequences in the cor- responding argument (except that \c terminates output, backslashes in \', \", and \? are not removed, and octal escapes beginning with \0 may contain up to four digits), and %q causes printf to output the corresponding argument in a format that can be reused as shell input . The -v option causes the output to be assigned to the variable var rather than being printed to the standard output. The format is reused as necessary to consume all of the arguments. If the format requires more arguments than are supplied, the extra format specifications behave as if a zero value or null string, as appropriate, had been supplied. The return value is zero on success, non-zero on failure. pushd [-n] [dir] pushd [-n] [+n] [-n] Adds a directory to the top of the directory stack, or rotates the stack, making the new top of the stack the current working directory. With no arguments, exchanges the top two directories and returns 0, unless the directory stack is empty. Arguments, if supplied, have the following meanings: +n Rotates the stack so that the nth directory (counting from the left of the list shown by dirs, starting with zero) is at the top. -n Rotates the stack so that the nth directory (counting from the right of the list shown by dirs, starting with zero) is at the top. -n Suppresses the normal change of directory when adding directories to the stack, so that only the stack is manipulated. dir Adds dir to the directory stack at the top, making it the new current working directory. If the pushd command is successful, a dirs is performed as well. If the first form is used, pushd returns 0 unless the cd to dir fails. With the second form, pushd returns 0 unless the directory stack is empty, a non-existent directory stack element is specified, or the directory change to the specified new current directory fails. pwd [-LP] Print the absolute pathname of the current working directory. The pathname printed contains no symbolic links if the -P option is supplied or the -o physical option to the set builtin command is enabled. If the -L option is used, the pathname printed may contain symbolic links. The return status is 0 unless an error occurs while reading the name of the current directory or an invalid option is supplied. read [-ers] [-u fd] [-t timeout] [-a aname] [-p prompt] [-n nchars] [-d delim] [name ...] One line is read from the standard input , or from the file descriptor fd supplied as an argument to the -u option, and the first word is assigned to the first name, the second word to the second name, and so on, with leftover words and their intervening separators assigned to the last name. If there are fewer words read from the input stream than names, the remaining names are assigned empty values. The characters in IFS are used to split the line into words. The backslash character (\) may be used to remove any special meaning for the next character read and for line continuation. Options, if supplied, have the following meanings: -a aname The words are assigned to sequential indices of the array variable aname, starting at 0. aname is unset before any new values are assigned. Other name arguments are ignored. -d delim The first character of delim is used to terminate the input line, rather than newline. -e If the standard input is coming from a terminal, readline (see READLINE above) is used to obtain the line. -n nchars read returns after reading nchars characters rather than waiting for a com- plete line of input . -p prompt Display prompt on standard error, without a trailing newline, before attempt- ing to read any input . The prompt is displayed only if input is coming from a terminal. -r Backslash does not act as an escape character. The backslash is considered to be part of the line. In particular, a backslash-newline pair may not be used as a line continuation. -s Silent mode. If input is coming from a terminal, characters are not echoed. -t timeout Cause read to time out and return failure if a complete line of input is not read within timeout seconds. This option has no effect if read is not reading input from the terminal or a pipe. -u fd Read input from file descriptor fd. If no names are supplied, the line read is assigned to the variable REPLY. The return code is zero, unless end-of- file is encountered, read times out, or an invalid file descriptor is supplied as the argument to -u. readonly [-apf] [name[=word] ...] The given names are marked readonly; the values of these names may not be changed by subsequent assignment. If the -f option is supplied, the functions corresponding to the names are so marked. The -a option restricts the variables to arrays. If no name arguments are given, or if the -p option is supplied, a list of all readonly names is printed. The -p option causes output to be displayed in a format that may be reused as input . If a variable name is followed by =word, the value of the vari- able is set to word. The return status is 0 unless an invalid option is encountered, one of the names is not a valid shell variable name, or -f is supplied with a name that is not a function. return [n] Causes a function to exit with the return value specified by n. If n is omitted, the return status is that of the last command executed in the function body. If used outside a function, but during execution of a script by the . (source) command, it causes the shell to stop executing that script and return either n or the exit status of the last command executed within the script as the exit status of the script. If used outside a function and not during execution of a script by ., the return status is false. Any command associated with the RETURN trap is executed before execution resumes after the function or script. set [--abefhkmnptuvxBCHP] [-o option] [arg ...] Without options, the name and value of each shell variable are displayed in a format that can be reused as input for setting or resetting the currently-set variables. Read-only variables cannot be reset. In posix mode, only shell variables are listed. The output is sorted according to the current locale. When options are specified, they set or unset shell attributes. Any arguments remaining after the options are processed are treated as values for the positional parameters and are assigned, in order, to $1, $2, ... $n. Options, if specified, have the following meanings: -a Automatically mark variables and functions which are modified or created for export to the environment of subsequent commands. -b Report the status of terminated background jobs immediately, rather than before the next primary prompt. This is effective only when job control is enabled. -e Exit immediately if a simple command (see SHELL GRAMMAR above) exits with a non-zero status. The shell does not exit if the command that fails is part of the command list immediately following a while or until keyword, part of the test in an if statement, part of a && or ││ list, or if the command’s return value is being inverted via !. A trap on ERR, if set, is executed before the shell exits. -f Disable pathname expansion. -h Remember the location of commands as they are looked up for execution. This is enabled by default. -k All arguments in the form of assignment statements are placed in the environ- ment for a command, not just those that precede the command name. -m Monitor mode. Job control is enabled. This option is on by default for interactive shells on systems that support it (see JOB CONTROL above). Back- ground processes run in a separate process group and a line containing their exit status is printed upon their completion. -n Read commands but do not execute them. This may be used to check a shell script for syntax errors. This is ignored by interactive shells. -o option-name The option-name can be one of the following: allexport Same as -a. braceexpand Same as -B. emacs Use an emacs-style command line editing interface. This is enabled by default when the shell is interactive, unless the shell is started with the --noediting option. errtrace Same as -E. functrace Same as -T. errexit Same as -e. hashall Same as -h. histexpand Same as -H. history Enable command history, as described above under HISTORY. This option is on by default in interactive shells. ignoreeof The effect is as if the shell command ‘‘IGNOREEOF=10’’ had been exe- cuted (see Shell Variables above). keyword Same as -k. monitor Same as -m. noclobber Same as -C. noexec Same as -n. noglob Same as -f. nolog Currently ignored. notify Same as -b. nounset Same as -u. onecmd Same as -t. physical Same as -P. pipefail If set, the return value of a pipeline is the value of the last (rightmost) command to exit with a non-zero status, or zero if all command
关注新的技术:Node.js家园 如何用 Perl 打印 文件 的某 几行 信息呢?假如你有一个 文件 ,你只关心某一段文字,大概你会使用比较传统的 文件 记数法,然后再来判断这个 文件 的区间是否在我们预期的之内。其它这个工作,在 Perl 是相当容易实现的。 use strict; open F,"c:/remoted.txt" or print "$^E";
1. 在 Perl ,注释由#开始,直到本 结束( Perl 没有“块注释”(block comments)) (1) 在Unix 系统 ◆,如果文本的第一 两个字符是“#!”,接着的就是执 下面 文件 的程序 #! /usr/bin/ perl print “Hello,word!\n” (2) 在非Unix 系统 ,传统上把第一 写做#! perl 。 2. s/\...
perl 式程序系列文章: Perl 式 对于 Perl 的一 perl 程序来说,选择要输出的、要删除的、要插入/追加的 是非常容易的事情,因为print/say决定 是否输出/插入/追加/删除。虽然简单,但对于广泛应用在sed的示例还是可以拿到这里来讨论一番。 因为输出/删除/插入/追加 都是通过print/say在不同条件下的操作,所以本文只会介绍输出操作,删除/插入/追加其实都是同样的原理...
可以使用 Perl 文件 操作函数来实现将大文本 文件 按照 指定 数分割成小文本 文件 的功能。 以下是一个示例代码,可以将大文本 文件 ` input .txt` 按照每个 文件 5000 的大小拆分成若干个小文本 文件 ,并以 `output_1.txt`、 `output_2.txt`、 `output_3.txt` ... 的方式命名保存。 ``` perl #!/usr/bin/ perl use strict; use warnings; # 每个输出 文件 数 my $lines_per_ file = 5000; # 输入 文件 名 my $ input _ file = " input .txt"; # 输出 文件 缀 my $output_ file _prefix = "output_"; # 初始化计数器和输出 文件 名 my $line_count = 0; my $ file _count = 1; my $output_ file = "$output_ file _prefix$ file _count.txt"; # 打开 输入 和输出 文件 open( INPUT , "<", $ input _ file ) or die "Cannot open $ input _ file for reading: $!"; open(OUTPUT, ">", $output_ file ) or die "Cannot open $output_ file for writing: $!"; # 逐 读取 输入 文件 并写入输出 文件 while (my $line = < INPUT >) { # 计数器加1 $line_count++; # 如果计数器达到了 指定 数,关闭当 输出 文件 并打开新的输出 文件 if ($line_count > $lines_per_ file ) { close(OUTPUT); $ file _count++; $output_ file = "$output_ file _prefix$ file _count.txt"; open(OUTPUT, ">", $output_ file ) or die "Cannot open $output_ file for writing: $!"; $line_count = 0; # 将当 写入输出 文件 print OUTPUT $line; # 关闭 输入 和输出 文件 close( INPUT ); close(OUTPUT); 这个代码 ,我们首先 指定 每个输出 文件 数 `$lines_per_ file ` 和 输入 文件 名 `$ input _ file `,然后初始化计数器和输出 文件 名,打开 输入 和输出 文件 。接着,我们逐 读取 输入 文件 ,并将当 写入输出 文件 。每当计数器达到了 指定 数时,关闭当 输出 文件 并打开新的输出 文件 ,重置计数器和输出 文件 名。 你可以根据实际需求修改代码 的参数,比如输出 文件 缀、每个输出 文件 数等等。
中文空格可设法避免: System.out.println((int)' '); //12288 System.out.println(Integer.toHexString(12288));//3000 System.out.println(&quot; &quot;.matches(&quot;[//u3000]&quot;)); //注意:上面的空格都是中文空格。 依据上面的正则式,在编辑器下可以查找到中文空格。 http://blog.csdn.net/willy2