关于watch命令的一些问题

[ryt]

为什么执行命令watch -d top,显示的结果很奇怪，如下:

Every 2.0s: top Wed Jan 7 17:55:17 2015

^[?1h^=^[?25l^[H^[2J^(B^[mtop - 17:55:18 up 1:29, 2 users, load average: 0.25, 0.25, 0.27^(B^[m^[39;49m^(B^[m^[39;49m^[K
Tasks:^(B^[m^[39;49m^[1m 211 ^(B^[m^[39;49mtotal,^(B^[m^[39;49m^[1m 1 ^(B^[m^[39;49mrunning,^(B^[m^[39;49m^[1m 210 ^(B^[m^[39;49msleeping,^(B^[m^[39;
49m^[1m 0 ^(B^[m^[39;49mstopped,^(B^[m^[39;49m^[1m 0 ^(B^[m^[39;49mzombie^(B^[m^[39;49m^(B^[m^[39;49m^[K
%Cpu(s):^(B^[m^[39;49m^[1m 5.8 ^(B^[m^[39;49mus,^(B^[m^[39;49m^[1m 2.0 ^(B^[m^[39;49msy,^(B^[m^[39;49m^[1m 0.0 ^(B^[m^[39;49mni,^(B^[m^[39;49m^[1m 9
0.9 ^(B^[m^[39;49mid,^(B^[m^[39;49m^[1m 1.4 ^(B^[m^[39;49mwa,^(B^[m^[39;49m^[1m 0.0 ^(B^[m^[39;49mhi,^(B^[m^[39;49m^[1m 0.0 ^(B^[m^[39;49msi,^(B^[m^
[39;49m^[1m 0.0 ^(B^[m^[39;49mst^(B^[m^[39;49m^(B^[m^[39;49m^[K
KiB Mem: ^(B^[m^[39;49m^[1m 1988032 ^(B^[m^[39;49mtotal,^(B^[m^[39;49m^[1m 1709340 ^(B^[m^[39;49mused,^(B^[m^[39;49m^[1m 278692 ^(B^[m^[39;49mfree,
^(B^[m^[39;49m^[1m 133448 ^(B^[m^[39;49mbuffers^(B^[m^[39;49m^(B^[m^[39;49m^[K
KiB Swap:^(B^[m^[39;49m^[1m 2018300 ^(B^[m^[39;49mtotal,^(B^[m^[39;49m^[1m 0 ^(B^[m^[39;49mused,^(B^[m^[39;49m^[1m 2018300 ^(B^[m^[39;49mfree.
^(B^[m^[39;49m^[1m 688100 ^(B^[m^[39;49mcached Mem^(B^[m^[39;49m^(B^[m^[39;49m^[K
^[K
^[7m PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
^(B^[m^[39;49m^[K
^(B^[m^[1m 4642 ryt 20 0 5552 1404 980 R 12.5 0.1 0:00.02 top
^(B^[m^[39;49m^[K
^(B^[m 1 root 20 0 4576 2560 1436 S 0.0 0.1 0:01.92 init
^(B^[m^[39;49m^[K
^(B^[m 2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd
^(B^[m^[39;49m^[K
^(B^[m 3 root 20 0 0 0 0 S 0.0 0.0 0:00.52 ksoftirqd/0
^(B^[m^[39;49m^[K
^(B^[m 5 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kworker/0:0H
^(B^[m^[39;49m^[K
^(B^[m 7 root 20 0 0 0 0 S 0.0 0.0 0:07.52 rcu_sched
^(B^[m^[39;49m^[K
^(B^[m 8 root 20 0 0 0 0 S 0.0 0.0 0:00.00 rcu_bh
^(B^[m^[39;49m^[K
^(B^[m 9 root rt 0 0 0 0 S 0.0 0.0 0:00.04 migration/0
^(B^[m^[39;49m^[K
^(B^[m 10 root rt 0 0 0 0 S 0.0 0.0 0:00.02 watchdog/0
^(B^[m^[39;49m^[K
^(B^[m 11 root rt 0 0 0 0 S 0.0 0.0 0:00.02 watchdog/1
^(B^[m^[39;49m^[K
^(B^[m 12 root rt 0 0 0 0 S 0.0 0.0 0:00.08 migration/1
^(B^[m^[39;49m^[K
^(B^[m 13 root 20 0 0 0 0 S 0.0 0.0 0:00.39 ksoftirqd/1
^(B^[m^[39;49m^[K
^(B^[m 15 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kworker/1:0H
^(B^[m^[39;49m^[K
^(B^[m 16 root rt 0 0 0 0 S 0.0 0.0 0:00.02 watchdog/2

请大家指教

[rosynirvana]

那些是终端的转义字符，你查一下就知道
另外top自己会刷新，为何要watch top

[susbarbatus]

因为 top 用了一些控制字符来获得特定显示效果，
终端能识别这些控制字符并显示了相应的结果，如 字体加粗、对齐、背景高亮等等，
而 watch 等工具只能识别纯文本，展示的时候将这些控制字符当作文本直接显示出来了。
关于这些控制字符，详细可以

代码： 全选

man 4 console_codes

[ryt]

那些是终端的转义字符，你查一下就知道
另外top自己会刷新，为何要watch top

只是试一下watch这个命令

[ryt]

因为 top 用了一些控制字符来获得特定显示效果，
终端能识别这些控制字符并显示了相应的结果，如 字体加粗、对齐、背景高亮等等，
而 watch 等工具只能识别纯文本，展示的时候将这些控制字符当作文本直接显示出来了。
关于这些控制字符，详细可以

代码： 全选

man 4 console_codes

明白了，谢谢

[vickycq]

搭车问一下如何watch多个命令？ 直接用&不行。

[EDIT] 试出来了，用引号括起来即可：

代码： 全选

watch -n 2 'commandA & commandB'