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Linux 的 more 命令

发表于 更新于 分类于 阅读次数： Disqus： Valine：

more - 多多益善

more功能类似 cat ，cat命令是整个文件的内容从上到下显示在屏幕上。 more会以一页一页的显示方便使用者逐页阅读，而最基本的指令就是按空白键（space）就往下一页显示，按 b 键就会往回（back）一页显示，而且还有搜寻字串的功能 。more命令从前向后读取文件，因此在启动时就加载整个文件。

在查阅文件的时候，我们说过可以用cat命令，不过这个是入门级别的，但凡用了几天Linux的，基本不太会再使用cat，而是另外两个指令，more或者less。这次说一下more，more是在文件的内容一个屏幕装不小的时候使用的。而less是more的升级版本，稍后会介绍。

more : 文件内容一屏幕装不下的时候使用的

看看为什么用less命令吧。

more - file perusal filter for crt viewing

看不懂，什么是CRT，莫慌，关于more的解释主要针对在上古年代的计算机，你不理解crt也没有关系，毕竟现在已经是Retina的年代了。

命令格式

less的命令格式与cat一样，可以直接跟上文件名，如下：

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less [参数] 文件

其中的参数如下所示：

  • +n 从笫n行开始显示
  • -n 定义屏幕大小为n行
  • +/pattern 在每个档案显示前搜寻该字串（pattern），然后从该字串前两行之后开始显示
  • -c 从顶部清屏，然后显示
  • -d 提示“Press space to continue，’q’ to quit（按空格键继续，按q键退出）”，禁用响铃功能
  • -l 忽略Ctrl+l（换页）字符
  • -p 通过清除窗口而不是滚屏来对文件进行换页，与-c选项相似
  • -s 把连续的多个空行显示为一行
  • -u 把文件内容中的下画线去掉

一起看看下面的实例吧，这里以文件/etc/services为例：

这个文件的开始信息如下：

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# /etc/services:
# $Id: services,v 1.55 2013/04/14 ovasik Exp $
#
# Network services, Internet style
# IANA services version: last updated 2013-04-10
#
# Note that it is presently the policy of IANA to assign a single well-known
# port number for both TCP and UDP; hence, most entries here have two entries
# even if the protocol doesn't support UDP operations.
# Updated from RFC 1700, ``Assigned Numbers'' (October 1994).  Not all ports
# are included, only the more common ones.
#
# The latest IANA port assignments can be gotten from
#       http://www.iana.org/assignments/port-numbers
# The Well Known Ports are those from 0 through 1023.
# The Registered Ports are those from 1024 through 49151
# The Dynamic and/or Private Ports are those from 49152 through 65535
#
# Each line describes one service, and is of the form:
#
# service-name  port/protocol  [aliases ...]   [# comment]

tcpmux          1/tcp                           # TCP port service multiplexer
tcpmux          1/udp                           # TCP port service multiplexer
rje             5/tcp                           # Remote Job Entry
rje             5/udp                           # Remote Job Entry
echo            7/tcp

+n 从第n行开始显示

接下来的命令从第10行开始显示：

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$ more +10 /etc/service

# Updated from RFC 1700, ``Assigned Numbers'' (October 1994).  Not all ports
# are included, only the more common ones.
#
# The latest IANA port assignments can be gotten from
#       http://www.iana.org/assignments/port-numbers
# The Well Known Ports are those from 0 through 1023.
# The Registered Ports are those from 1024 through 49151
# The Dynamic and/or Private Ports are those from 49152 through 65535
#
# Each line describes one service, and is of the form:
#
# service-name  port/protocol  [aliases ...]   [# comment]

tcpmux          1/tcp                           # TCP port service multiplexer
tcpmux          1/udp                           # TCP port service multiplexer
rje             5/tcp                           # Remote Job Entry
rje             5/udp                           # Remote Job Entry
echo            7/tcp
echo            7/udp
discard         9/tcp           sink null
discard         9/udp           sink null
systat          11/tcp          users
systat          11/udp          users
daytime         13/tcp
daytime         13/udp
qotd            17/tcp          quote
qotd            17/udp          quote

可以看到前面的10行是没有显示的。

-n 定义屏幕大小为n行

这里的含义为定义输出的内容为10行，你的屏幕可能足够大，不过显示的内容只有n行，如下：只显示10行的内容，此时终端可能还会残留以前的内容：

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$ more -10 /etc/services
# /etc/services:
# $Id: services,v 1.55 2013/04/14 ovasik Exp $
#
# Network services, Internet style
# IANA services version: last updated 2013-04-10
#
# Note that it is presently the policy of IANA to assign a single well-known
# port number for both TCP and UDP; hence, most entries here have two entries
# even if the protocol doesn't support UDP operations.
# Updated from RFC 1700, ``Assigned Numbers'' (October 1994).  Not all ports

可以关注一下，此时每次显示的只有10行。

+/pattern 搜寻字符串（pattern）

这个参数用于在文件中搜索字符串pattern，然后在该字符串的前两行之前开始显示。比如搜索number，会显示以下内容：

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$ more +/number /etc/services
#
# Note that it is presently the policy of IANA to assign a single well-known
# port number for both TCP and UDP; hence, most entries here have two entries
# even if the protocol doesn't support UDP operations.
# Updated from RFC 1700, ``Assigned Numbers'' (October 1994).  Not all ports
# are included, only the more common ones.
#
# The latest IANA port assignments can be gotten from
#       http://www.iana.org/assignments/port-numbers
# The Well Known Ports are those from 0 through 1023.
# The Registered Ports are those from 1024 through 49151
# The Dynamic and/or Private Ports are those from 49152 through 65535
#
# Each line describes one service, and is of the form:
#
# service-name  port/protocol  [aliases ...]   [# comment]

tcpmux          1/tcp                           # TCP port service multiplexer
tcpmux          1/udp                           # TCP port service multiplexer
rje             5/tcp                           # Remote Job Entry
rje             5/udp                           # Remote Job Entry
echo            7/tcp
echo            7/udp
discard         9/tcp           sink null
discard         9/udp           sink null
systat          11/tcp          users
systat          11/udp          users
daytime         13/tcp
......

可以留意，此时显示的内容，第三行即包含搜索的字符串。

其他

除以上介绍的以外，还有比较容易理解的以下参数：

  • -c 从顶部清屏，然后显示
  • -p 通过清除窗口而不是滚屏来对文件进行换页，与-c选项相似
  • -s 把连续的多个空行显示为一行
  • -u 把文件内容中的下画线去掉
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