LINUX: Grep 命令去空行

今天学习了 grep 命令一个小技巧，即 “去空行”， grep 命令能够非常方便地查看配置文件哪些参数被修改了，今天测试了把，用来处理 PostgreSQL 的配置文件 postgresql.conf。

1 查看 postgresql.conf 文件中被修改的参数

[postgres@redhat6 pg_root]$ cat postgresql.conf | grep -v "^$" | grep -v "^#"
 # (change requires restart)  
 # (change requires restart)  
 # (change requires restart)  
 # (change requires restart)  
listen_addresses = '*' # what IP address(es) to listen on;  
 # comma-separated list of addresses;  
 # defaults to 'localhost'; use '*' for all  
 # (change requires restart)  
port = 1922 # (change requires restart)  
max_connections = 100 # (change requires restart)  
 # (change requires restart)  
 # (change requires restart)  
 # (change requires restart)  
 # (change requires restart)  
 # 0 selects the system default  
 # 0 selects the system default  
 # 0 selects the system default  
shared_buffers = 32MB # min 128kB  
 # (change requires restart)  
 # (change requires restart)  
 # in kB, or -1 for no limit  
 # (change requires restart)  
wal_level = archive # minimal, archive, or hot_standby  
 # (change requires restart)  
 # off, local, remote_write, or on  
 # supported by the operating system:  
 # open_datasync  
 # fdatasync (default on Linux)  
 # fsync  
 # fsync_writethrough  
 # open_sync  
 # (change requires restart)  
checkpoint_segments = 3 # in logfile segments, min 1, 16MB each  
checkpoint_timeout = 2min # range 30s-1h  
checkpoint_completion_target = 0.5 # checkpoint target duration, 0.0 - 1.0  
archive_mode = on # allows archiving to be done  
 # (change requires restart)  
archive_command = '/bin/date' # command to use to archive a logfile segment
...
..省略部分

备注：符号 ^ 表示匹配一行的开始； $ 表示匹配一行的结束; 所示 ^# 表示空行。因此去掉 postgresql.conf 中的空行，并且排除掉以 # 打头的行，即为已更改的配置文件参数。

2 查看 postgreql.conf 中值为 “on” 的参数

[postgres@redhat6 pg_root]$ cat postgresql.conf | grep "= on$" | grep -v "^#"  
log_checkpoints = on  
log_connections = on  
track_activities = on

3 查看 postgreql.conf 中值为 “off” 的参数

1 2	[postgres@redhat6 pg_root]$ cat postgresql.conf \| grep "= off$" \| grep -v "^#" log_disconnections = off

4 附件 postgresql.conf
本来想上传 postgresql.conf ，网易 blog 居然不支持上传txt 格式文件，熟悉 postgresql 的朋友应该都知道这个配置文件，这里就不上传了。

原创文章，作者：奋斗，如若转载，请注明出处：https://blog.ytso.com/237894.html

LINUX: Grep 命令去空行

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