col
col功能说明：过滤控制字符。
语 法：col [-bfx][-l<缓冲区列数>]
补充说明：在许多UNIX说明文件里，都有RLF控制字符。当我们运用shell特殊字符">"和">>"，把说明文件的内容输出成纯文本文件时，控制字符会变成乱码，col指令则能有效滤除这些控制字符。
参 数：
-b 过滤掉所有的控制字符，包括RLF和HRLF。
-f 滤除RLF字符，但允许将HRLF字符呈现出来。
-x 以多个空格字符来表示跳格字符。
-l<缓冲区列数> 预设的内存缓冲区有128列，您可以自行指定缓冲区的大小。
col
col [options]
A postprocessing filter that handles reverse linefeeds and escape characters, allowing output from tbl or nroff to appear in reasonable form on a terminal.
Options
Ignore backspace characters; helpful when printing manpages.
Process half-line vertical motions, but not reverse line motion. (Normally, half-line input motion is displayed on the next full line.)
Buffer at least n lines in memory. The default buffer size is 128 lines.
Normally, col saves printing time by converting sequences of spaces to tabs. Use -x to suppress this conversion.
Examples
Run myfile through tbl and nroff, then capture output on screen by filtering through col and more:
tbl myfile | nroff | col | more
Save manpage output for the ls command in out.print, stripping out backspaces (which would otherwise appear as ^H):
man ls | col -b > out.print