cat
cat使用权限：所有使用者
使用方式：cat [-AbeEnstTuv] [--help] [--version] fileName
说 明：把档案串连接后传到基本输出（萤幕或加 > fileName 到另一个档案）
参 数：
-n 或 --number 由 1 开始对所有输出的行数编号
-b 或 --number-nonblank 和 -n 相似，只不过对于空白行不编号
-s 或 --squeeze-blank 当遇到有连续两行以上的空白行，就代换为一行的空白行
-v 或 --show-nonprinting
范例：
cat -n textfile1 > textfile2 把 textfile1 的档案内容加上行号后输入 textfile2 这个档案里
cat -b textfile1 textfile2 >> textfile3 把 textfile1 和 textfile2 的档案内容加上行号（空白行不加）之后将内容附加到 textfile3 里。
cat
cat [options] [files]
Read (concatenate) one or more files and print them on standard output. Read standard input if no files are specified or if - is specified as one of the files; input ends with EOF. You can use the > operator to combine several files into a new file, or >> to append files to an existing file. When appending to an existing file, use Ctrl-D, the end-of-file symbol, to end the session.
Options
Same as -vET.
Number all nonblank output lines, starting with 1.
Same as -vE.
Print $ at the end of each line.
Number all output lines, starting with 1.
Squeeze down multiple blank lines to one blank line.
Same as -vT.
Print TAB characters as ^I.
Ignored; retained for Unix compatibility.
Display control and nonprinting characters, with the exception of LINEFEED and TAB.
Examples
cat ch1