替换文本中的字符串
    sed ‘s/book/books/‘ file

    匹配file文件中每一行的第一个book替换为books
    sed -i ‘s/book/books/g’ file

    全面替换
    sed ‘s/book/books/g’ file

    从第n处开始替换
    echo sksksksksksk | sed ‘s/sk/SK/2g’
    skSKSKSKSKSK

    删除空白行
    sed ‘/^$/d’ file

    已匹配字符串标记&
    sed ‘s/^192.168.0.1/&localhost/‘ file
    192.168.0.1localhost

    选定行的范围: , (逗号)
    所有在模板test和check所确定的范围内的行都被打印：
    sed -n ‘/test/,/check/p’ file