网站一般用什么服务器收录查询站长工具

平时查看某些配置文件的时，我们会发现有很多注释（如："#"开头的行），中间还有很多空行，看起来非常费劲，所以在这里总结下如何去除注释和空行的方法。

举例说明
这里选个简单点的文件，来演示下效果，我们可以看到一些空行和注释。

rdb-save-incremental-fsync yes# Redis LFU eviction (see maxmemory setting) can be tuned. However it is a good
# idea to start with the default settings and only change them after investigating
# how to improve the performances and how the keys LFU change over time, which
# is possible to inspect via the OBJECT FREQ command.
#
# There are two tunable parameters in the Redis LFU implementation: the
# counter logarithm factor and the counter decay time. It is important to
# understand what the two parameters mean before changing them.
#
# The LFU counter is just 8 bits per key, it's maximum value is 255, so Redis
# uses a probabilistic increment with logarithmic behavior. Given the value
# of the old counter, when a key is accessed, the counter is incremented in
# this way:
#
# 1. A random number R between 0 and 1 is extracted.
# 2. A probability P is calculated as 1/(old_value*lfu_log_factor+1).
# 3. The counter is incremented only if R < P.
#
# The default lfu-log-factor is 10. This is a table of how the frequency
# counter changes with a different number of accesses with different
# logarithmic factors:
#
# +--------+------------+------------+------------+------------+------------+
# | factor | 100 hits   | 1000 hits  | 100K hits  | 1M hits    | 10M hits   |
# +--------+------------+------------+------------+------------+------------+
# | 0      | 104        | 255        | 255        | 255        | 255        |
# +--------+------------+------------+------------+------------+------------+
# | 1      | 18         | 49         | 255        | 255        | 255        |
# +--------+------------+------------+------------+------------+------------+
# | 10     | 10         | 18         | 142        | 255        | 255        |
# +--------+------------+------------+------------+------------+------------+
# | 100    | 8          | 11         | 49         | 143        | 255        |
# +--------+------------+------------+------------+------------+------------+
#
# NOTE: The above table was obtained by running the following commands:
#

去除注释和空行的命令
使用 tr命令

grep -v "#" /etc/yum.conf |tr -s '\n'

效果

使用 sed命令

grep -v "#" /etc/yum.conf|sed '/^$/d'

效果和上面一样，这里就不继续贴图了。

使用 awk命令

grep -v "#" /etc/yum.conf |awk '{if($0!="")print}'

使用 grep命令

grep -v "#" /etc/yum.conf |grep -v "^$"