3.21-22 od、tee

[root@cs7-sm ~]# file /bin/ls    #<一像ls命令是一个二进制命令，通过cat命令查看会发现一堆乱码。
/bin/ls: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.32, BuildID[sha1]=ceaf496f3aec08afced234f4f36330d3d13a657b, stripped
[root@cs7-sm ~]# od -Ax -tcx /bin/ls|more
000000 177   E   L   F 002 001 001  \0  \0  \0  \0  \0  \0  \0  \0  \0
              464c457f        00010102        00000000        00000000
000010 002  \0   >  \0 001  \0  \0  \0 324   B   @  \0  \0  \0  \0  \0
              003e0002        00000001        004042d4        00000000
000020   @  \0  \0  \0  \0  \0  \0  \0 360 303 001  \0  \0  \0  \0  \0
              00000040        00000000        0001c3f0        00000000
000030  \0  \0  \0  \0   @  \0   8  \0  \t  \0   @  \0 037  \0 036  \0
              00000000        00380040        00400009        001e001f
000040 006  \0  \0  \0 005  \0  \0  \0   @  \0  \0  \0  \0  \0  \0  \0
              00000006        00000005        00000040        00000000
000050   @  \0   @  \0  \0  \0  \0  \0   @  \0   @  \0  \0  \0  \0  \0
              00400040        00000000        00400040        00000000
000060 370 001  \0  \0  \0  \0  \0  \0 370 001  \0  \0  \0  \0  \0  \0
              000001f8        00000000        000001f8        00000000

[root@cs7-sm ~]# ls |tee test1
gb2312.txt
test1
test2
test_win.sh
[root@cs7-sm ~]# cat test1    #<==ls命令接管通和tee命令，在屏靠上输出ls的结果，同时将结果写入到test1.txt。会清空原有的内容
gb2312.txt
test1
test2
test_win.sh

[root@cs7-sm ~]# ls |tee -a ls test1   #<==使用参数-a可以追加内容到文件中，不会清空文件中已有的内容。
gb2312.txt
ls
test1
test2
test_win.sh
[root@cs7-sm ~]# cat test1
gb2312.txt
test1
test2
test_win.sh
gb2312.txt
ls
test1
test2
test_win.sh