shell環境中，echo是常用的數據命令，但有的時候，想通過“\n”使輸出換行卻換不了，這個時候需要增加-e選項：
$ echo "Hellow.\nHey man~" Hellow.\nHey man~ $ echo -e "Hellow.\nHey man~" Hellow. Hey man~
查看echo手冊：
ECHO(1) User Commands ECHO(1) NAME echo - display a line of text SYNOPSIS echo [SHORT-OPTION]... [STRING]... echo LONG-OPTION DESCRIPTION Echo the STRING(s) to standard output. -n do not output the trailing newline -e enable interpretation of backslash escapes -E disable interpretation of backslash escapes (default) --help display this help and exit --version output version information and exit If -e is in effect, the following sequences are recognized: \\ backslash \a alert (BEL) \b backspace \c produce no further output \e escape \f form feed \n new line \r carriage return \t horizontal tab \v vertical tab \0NNN byte with octal value NNN (1 to 3 digits) \xHH byte with hexadecimal value HH (1 to 2 digits) NOTE: your shell may have its own version of echo, which usually supersedes the version described here. Please refer to your shell’s documentation for details about the options it supports. AUTHOR Written by Brian Fox and Chet Ramey.
可以看到-e的作用是使帶反斜杠'\'的轉義符生效。因此想讓\n生效，必須帶上-e選項。