注意参数-n

(1)显示某一行或某些行

显示1,10行
$ sed -n '1,10p' postgres.conf

显示第10行
$ sed -n '10p' postgres.conf

(2)显示某些匹配行
$ sed -n '/This/p' postgres.conf

我的测试：

XYZ@XYZ-desktop:~$ sed -n '1,10 p' postgresql.conf  
# -----------------------------
# PostgreSQL configuration file
# -----------------------------
#
# This file consists of lines of the form:
#
#   name = value
#
# (The "=" is optional.)  Whitespace may be used.  Comments are introduced with
# "#" anywhere on a line.  The complete list of parameter names and allowed
XYZ@XYZ-desktop:~$ sed -n '10p' postgresql.conf 
# "#" anywhere on a line.  The complete list of parameter names and allowed
XYZ@XYZ-desktop:~$ sed -n '/This/p' postgresql.conf 
# This file consists of lines of the form:
# This file is read on server startup and when the server receives a SIGHUP
# This is used when logging to stderr:
XYZ@XYZ-desktop:~$ 


下面的部分来自网上，对于上面的理解会更充分：

Relations between d, p, and !
  Sed	   Range   Command   Results
  --------------------------------------------------------
  sed -n   1,10	   p	     Print first 10 lines
  sed -n   11,$	   !p	     Print first 10 lines
  sed	   1,10	   !d	     Print first 10 lines
  sed	   11,$	   d	     Print first 10 lines
  --------------------------------------------------------
  sed -n   1,10	   !p	     Print last 10 lines
  sed -n   11,$	   p	     Print last 10 lines
  sed	   1,10	   d	     Print last 10 lines
  sed	   11,$	   !d	     Print last 10 lines
  --------------------------------------------------------
  sed -n   1,10	   d	     Nothing printed
  sed -n   1,10	   !d	     Nothing printed
  sed -n   11,$	   d	     Nothing printed
  sed -n   11,$	   !d	     Nothing printed
  --------------------------------------------------------
  sed	   1,10	   p	     Print first 10 lines twice,
			     Then next 10 lines once
  sed	   11,$	   !p	     Print first 10 lines twice,
			     Then last 10 lines once
  --------------------------------------------------------
  sed	   1,10	   !p	     Print first 10 lines once,
			     Then last 10 lines twice
  sed	   11,$	   p	     Print first 10 lines once,
			     then last 10 lines twice

This table shows that the following commands are identical:

sed -n '1,10 p'
sed -n '11,$ !p'
sed '1,10 !d'
sed '11,$ d'





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