Perl 单行编辑技巧

Perl 有一些简单的单行技巧，可以帮助很方便的实现一些文件编辑查找。介绍几个常用的方法：

C:\>perl -h

Usage: D:\Perl\bin\perl.exe [switches] [--] [programfile] [arguments]
  -0[octal]         specify record separator (\0, if no argument)
  -a                autosplit mode with -n or -p (splits $_ into @F)
  -C[number/list]   enables the listed Unicode features
  -c                check syntax only (runs BEGIN and CHECK blocks)
  -d[:debugger]     run program under debugger
  -D[number/list]   set debugging flags (argument is a bit mask or alphabets)
  -e program        one line of program (several -e's allowed, omit programfile)
  -E program        like -e, but enables all optional features
  -f                don't do $sitelib/sitecustomize.pl at startup
  -F/pattern/       split() pattern for -a switch (//'s are optional)
  -i[extension]     edit <> files in place (makes backup if extension supplied)
  -Idirectory       specify @INC/#include directory (several -I's allowed)
  -l[octal]         enable line ending processing, specifies line terminator
  -[mM][-]module    execute "use/no module..." before executing program
  -n                assume "while (<>) { ... }" loop around program
  -p                assume loop like -n but print line also, like sed
  -P                run program through C preprocessor before compilation
  -s                enable rudimentary parsing for switches after programfile
  -S                look for programfile using PATH environment variable
  -t                enable tainting warnings
  -T                enable tainting checks
  -u                dump core after parsing program
  -U                allow unsafe operations
  -v                print version, subversion (includes VERY IMPORTANT perl info)
  -V[:variable]     print configuration summary (or a single Config.pm variable)
  -w                enable many useful warnings (RECOMMENDED)
  -W                enable all warnings
  -x[directory]     strip off text before #!perl line and perhaps cd to directory
  -X                disable all warnings

perl -ne 'scirpt' filename

循环读入文件并根据脚本处理每一行

perl -pe 'scirpt' filename

循环读入文件并根据脚本处理每一行，不同的是打印处理后每一行的内容

perl -i.bak -pe 's/string1/string2/g' filename

替换文件中每一行的字符串string1，并将原始文件备份为.bak。注意，替换的时候需要使用参数p

perl -ne 'print if 1..10' filename

对文件的前10行处理，行数从1开始计算

perl -ne 'print if /START/../END/' filename

对文件内容，从包含START 行开始打印，到包含END行结束。如果包含多个这样的段落，都打印出来，如果没有行包含END，则打印到文件结束

最后看一下实际执行中的代码

D:\Tmp>perl -MO=Deparse -ne "print if 1..10" test.pl
LINE: while (defined($_ = <ARGV>)) {
    print $_ if 1 .. 10;
}
-e syntax OK

D:\Tmp>perl -MO=Deparse -pe "print if 1..10" test.pl
LINE: while (defined($_ = <ARGV>)) {
    print $_ if 1 .. 10;
}
continue {
    print $_;
}
-e syntax OK