bash正则表达式

一、正则表达式与通配符

二、基础正则表达式

2.1 “*”匹配符

###找出redis.conf文件中含有0到多个a的行（不要理解成含有a或以a打头的行），该正则无任何意义，实际上是列出所有内容
[root@wenhaijin tmp]# grep "a*" redis.conf

###找出内容中含有redi,后面接0或多个s的行
[root@wenhaijin tmp]# grep "redis*" redis.conf
# ./redis-server /path/to/redis.conf
# unixsocket /tmp/redis.sock
pidfile /var/run/redis_6379.pid
# others with access to the host running redis-server.
[root@wenhaijin tmp]#

###找出包含至少有两个连续t的行，并高亮显示tt(工具原因，这边高亮没发展示出来)
[root@wenhaijin tmp]# grep "ttt*" redis.conf  --color auto
# to customize a few per-server settings.  Include files can include
# Notice option "include" won't be rewritten by command "CONFIG REWRITE"
# line as value of a configuration directive, you'd better put includes
# options, it is better to use include as the last line.
# synchronization". An RDB file is transmitted from the master to the slaves.
# works better.
# repl-backlog-ttl 3600
# A slave with a low priority number is considered better for promotion, so
# Setting one or the other to 0 disables the feature.
# A Redis master is able to list the address and port of the attached
# Warning: since Redis is pretty fast an outside user can try up to
# AOF file or transmitted to slaves may cause problems.
# WARNING: If you have slaves attached to an instance with maxmemory on,
# In short... if you have slaves attached it is suggested that you set a lower
# volatile-ttl -> remove the key with the nearest expire time (minor TTL)
# Both the hard or the soft limit can be disabled by setting them to zero.

2.2 “.”匹配符

###匹配c和f之间有两个字符的行
[root@wenhaijin tmp]# grep "c..f" --color  redis.conf

###匹配featur和e之间有任意字符的行
[root@wenhaijin tmp]# grep "featur.*e" redis.conf
# Setting one or the other to 0 disables the feature.
# By default min-slaves-to-write is set to 0 (feature disabled) and
[root@wenhaijin tmp]#

2.3 “^”匹配行首，"$"匹配行尾

###匹配以小写"z"打头的行
[root@wenhaijin tmp]# grep "^z" redis.conf
zset-max-ziplist-entries 128
zset-max-ziplist-value 64
[root@wenhaijin tmp]#

###匹配以小写"m"结尾的行
[root@wenhaijin tmp]# grep "m$" redis.conf
# The lag in seconds, that must be <= the specified value, is calculated from
# volatile-lru -> remove the key with an expire set using an LRU algorithm
# allkeys-lru -> remove any key according to the LRU algorithm
[root@wenhaijin tmp]#

###匹配空白行 -n显示行号
[root@wenhaijin tmp]# grep -n "^$" redis.conf
7:
19:
21:
37:
321:
323:
326:
330:
335:
[root@wenhaijin tmp]#

2.4 "[]"匹配中括号中指定的任意一个字符

###匹配Bath或者Both或者Buth
[root@wenhaijin tmp]# grep "B[aou]th" redis.conf
# Both the hard or the soft limit can be disabled by setting them to zero.
# Bath the hard or the soft limit can be disabled by setting them to zero.
# Buth the hard or the soft limit can be disabled by setting them to zero.
[root@wenhaijin tmp]#

###匹配包含任意数字的行（行数太多，不黏进来）
[root@wenhaijin tmp]# grep "[0-9]" redis.conf

###匹配以任意数字开头的行
[root@wenhaijin tmp]# grep "^[0-9]" redis.conf
[root@wenhaijin tmp]#

###如果^在中括号里面则表示取反
###显示不是以数字打头的行，（行数太多，不黏进来）
[root@wenhaijin tmp]# grep "^[^0-9]" redis.conf

2.5 “\”转义字符

###匹配以英文句号结尾的行，结果太多不黏进来，如果没有"\"则匹配以任意一个字符结尾的行
[root@wenhaijin tmp]# grep "\.$" redis.conf

###匹配连续出现三个i的行
[root@wenhaijin tmp]# grep "i\{3\}" redis.conf
# biiig latency spikes.
[root@wenhaijin tmp]#

###匹配至少有5个连续数字的行
[root@wenhaijin tmp]# grep "[0-9]\{5\}" redis.conf
# 1m => 1000000 bytes
# 1g => 1000000000 bytes
# Accept connections on the specified port, default is 6379 (IANA #815344).
save 60 10000
# rename-command CONFIG b840fc02d524045429941cc15f59e41cb7be6c52
# this limit is set to 10000 clients, however if the Redis server is not
# maxclients 10000
[root@wenhaijin tmp]#

###匹配至少出现连续5个数字的行
[root@wenhaijin tmp]# grep "[0-9]\{5,\}" redis.conf
# 1m => 1000000 bytes
# 1g => 1000000000 bytes
# Accept connections on the specified port, default is 6379 (IANA #815344).
save 60 10000
# rename-command CONFIG b840fc02d524045429941cc15f59e41cb7be6c52
# this limit is set to 10000 clients, however if the Redis server is not
# maxclients 10000
[root@wenhaijin tmp]#

###列出最少连续4个数字，最多连续5个数字的行
[root@wenhaijin tmp]# grep "[0-9]\{4,5\}" redis.conf
# 1k => 1000 bytes
# 1kb => 1024 bytes
# 1m => 1000000 bytes
# 1mb => 1024*1024 bytes
# 1g => 1000000000 bytes
# 1gb => 1024*1024*1024 bytes
# Accept connections on the specified port, default is 6379 (IANA #815344).
port 6379
pidfile /var/run/redis_6379.pid
save 60 10000
# repl-backlog-ttl 3600
# slave-announce-port 1234
# rename-command CONFIG b840fc02d524045429941cc15f59e41cb7be6c52
# this limit is set to 10000 clients, however if the Redis server is not
# maxclients 10000
[root@wenhaijin tmp]#

###列出b和g之间最少2个i，最多3个i的行
[root@wenhaijin tmp]# grep "bi\{2,3\}g" redis.conf
# biiig latency spikes.
[root@wenhaijin tmp]#