linux下查看文件内容cat,more,less

$ cat --h
Usage: cat [OPTION] [FILE]...
Concatenate FILE(s), or standard input, to standard output.

  -A, --show-all           equivalent to -vET
                           与-vET等价
  -b, --number-nonblank    number nonblank output lines
                           输出行号，只针对非空白行
  -e                       equivalent to -vE
                           与-vE等价
  -E, --show-ends          display $ at end of each line
                           文件末尾展示$

  -n, --number             number all output lines
                           输出行号
  -s, --squeeze-blank      never more than one single blank line
                           合并多个空白行，只输出一行
  -t                       equivalent to -vT
  -T, --show-tabs          display TAB characters as ^I
                           将 TAB 展示为^I
  -v, --show-nonprinting   use ^ and M- notation, except for LFD and TAB
                           展示一些看不出来的字符

$ cat 1
hello   world


hello   linux

$ cat -n 1
     1  hello   world
     2
     3
     4  hello   linux
     5

$ cat -A 1 
hello^Iworld^M$
^M$
^M$
hello^Ilinux^M$
^M$

3. more命令

$ more filename

4. less命令

$ less filename