grep 命令系列：如何只查看配置文件中未被注釋的有效配置行

grep 命令示例——去掉注釋

可以按照如下示例使用grep命令:

$ grep -v "^#" /path/to/config/file
$ grep -v "^#" /etc/apache2/apache2.conf

示例輸出:

ServerRoot "/etc/apache2"

LockFile /var/lock/apache2/accept.lock

PidFile ${APACHE_PID_FILE}

Timeout 300

KeepAlive On

MaxKeepAliveRequests 100

KeepAliveTimeout 15

<IfModule mpm_prefork_module>
    StartServers          5
    MinSpareServers       5
    MaxSpareServers      10
    MaxClients          150
    MaxRequestsPerChild   0
</IfModule>

<IfModule mpm_worker_module>
    StartServers          2
    MinSpareThreads      25
    MaxSpareThreads      75
    ThreadLimit          64
    ThreadsPerChild      25
    MaxClients          150
    MaxRequestsPerChild   0
</IfModule>

<IfModule mpm_event_module>
    StartServers          2
    MaxClients          150
    MinSpareThreads      25
    MaxSpareThreads      75
    ThreadLimit          64
    ThreadsPerChild      25
    MaxRequestsPerChild   0
</IfModule>

User ${APACHE_RUN_USER}
Group ${APACHE_RUN_GROUP}

AccessFileName .htaccess

<Files ~ "^.ht">
    Order allow,deny
    Deny from all
    Satisfy all
</Files>

DefaultType text/plain

HostnameLookups Off

ErrorLog /var/log/apache2/error.log

LogLevel warn

Include /etc/apache2/mods-enabled/*.load
Include /etc/apache2/mods-enabled/*.conf

Include /etc/apache2/httpd.conf

Include /etc/apache2/ports.conf

LogFormat "%v:%p %h %l %u %t "%r" %>s %O "%{Referer}i" "%{User-Agent}i"" vhost_combined
LogFormat "%h %l %u %t "%r" %>s %O "%{Referer}i" "%{User-Agent}i"" combined
LogFormat "%h %l %u %t "%r" %>s %O" common
LogFormat "%{Referer}i -> %U" referer
LogFormat "%{User-agent}i" agent

CustomLog /var/log/apache2/other_vhosts_access.log vhost_combined

Include /etc/apache2/conf.d/

Include /etc/apache2/sites-enabled/

想要跳過其中的空行，可以使用 egrep 命令, 示例:

egrep -v "^#|^$" /etc/apache2/apache2.conf
## or pass it to the page such as more or less ##
egrep -v "^#|^$" /etc/apache2/apache2.conf | less

## Bash function ######################################
## or create function or alias and use it as follows ##
## viewconfig /etc/squid/squid.conf                  ##
#######################################################
viewconfig(){
   local f="$1"
   [ -f "$1" ] && command egrep -v "^#|^$" "$f" || echo "Error $1 file not found."
}

示例輸出:

圖 01: Unix/Linux Egrep 除去注釋行和空行

理解 grep/egrep 命令行選項

-v 選項，選擇出不匹配的命令行。該選項適用於所有基於posix的系統。正則表達式 ^$ 匹配出所有的非空行， ^# 匹配出所有的不以「#」開頭的非注釋行。

sed 命令示例

可以按照如下示例使用 GNU 上的 sed 命令:

$ sed '/ *#/d; /^ *$/d' /path/to/file
$ sed '/ *#/d; /^ *$/d' /etc/apache2/apache2.conf

GNU 或 BSD 上的 sed 也可以修改配置文件。下面的命令的作用是原地編輯文件，並以特定（比如 .bak）備份文件：

sed -i'.bak.2015.12.27' '/ *#/d; /^ *$/d' /etc/apache2/apache2.conf

更多信息見參考手冊 - grep(1), sed(1)。

via: http://www.cyberciti.biz/faq/shell-display-uncommented-lines-only/

作者：Vivek Gite 譯者：sonofelice 校對：wxy

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本文轉載來自 Linux 中國: https://github.com/Linux-CN/archive