一个修改配置文件的linux shell script
来源：程序员人生 发布时间：2014-11-04 09:01:01 阅读次数：3255次
不久之前，曾搜到1篇博客是读取配置文件的，http://www.cnblogs.com/bo083/archive/2012/11/19/2777076.html，用到现在，感觉10分方便，感谢作者。
现在，需要通过web界面给用户留出接口来修改类似配置文件，大的方法是从php调用linux shell script，因而，现在贴1个可以修改此种配置文件的linux shell。
首先，配置文件的格式以下：
[unit1]
field1=value1
field2=value2
[unit2]
field1=value3
field3=value4
...
...
例子以下，config.ini：
[DATABASE]
dbms_ip=localhost
user=root
passwd=cloud
db_name=cloud
port=2394
[BUSINESS]
port=9084
[OFFLINE]
pcap_file=test.pcap
配置文件中包括3个unit，表示3个大的方面：http://www.wfuyu.com/db/，业务，离线；每一个unit有属于自己的字段名及字段值。
上文中援用博客正是能读取这样的配置文件，而目前我们便是要通过linux shell来修改这个配置文件。
我们设计的程序名为 modify_config_file，使用 ./modify_config_file unit1-field1=changed_value1 unit2-field1=changed_value2 这样的格式（参数可以继续添加）来进行修改。
要做到修改配置文件的功能其实其实不难，20⑶0行即可以解决问题。但是基于“1切输入都是有害的”的原则，需要在shell中加入各种容错处理，如果用户参数输入毛病，要能及时提示用户，定位问题所在，下面是基于这样1个初衷的shell，固然，名称为modify_config_file：
#!/bin/bash
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin
export PATH
#Program
# This program is to modify the configuration file
#History
# 2014.10.30 WeiZheng 1.1
MY_HOME="/home/weizheng/10⑶0-yg/yg-soft"
CONFIG_FILE="$MY_HOME/config.ini"
ERROR_NUM=255
function get_line_num()
{
# Check if the argument name has the separator "-" that separate the argument unit and argument field
separator=$(echo $1 | grep "-")
if [ -z "$separator" ]; then
echo -e "error: "$1": argument name has no separator "-" that separate the argument unit and argument field"
exit $ERROR_NUM
fi
# Check if the argument name has argument unit and argument field
arg_unit=$(echo $1 | cut -d "-" -f 1)
arg_field=$(echo $1 | cut -d "-" -f 2)
if [ -z "$arg_unit" -o -z "$arg_field" ]; then
echo -e "error: "$1": argument name has no argument unit or argument field around "-""
exit $ERROR_NUM
fi
# Get the argument unit's interval [$arg_unit_line_num, $next_neighbour_unit_line_num)
arg_unit_line_num=$(grep -n "[$arg_unit]" $CONFIG_FILE | cut -d ":" -f1)
if [ -z "$arg_unit_line_num" ]; then
echo -e "error: "$arg_unit": can not find argument unit"
exit $ERROR_NUM
fi
next_neighbour_unit_line_num=$(awk "NR>$arg_unit_line_num && /^[.*]/ {print NR; exit 0}" $CONFIG_FILE)
if [ -z "$next_neighbour_unit_line_num" ]; then
file_line_count=$(wc -l $CONFIG_FILE | cut -d " " -f 1)
next_neighbour_unit_line_num=$((file_line_count+1))
fi
echo "argument unit interval: ($arg_unit_line_num, $next_neighbour_unit_line_num)"
arg_field_line_nums=$(grep -n "^$arg_field=" $CONFIG_FILE | cut -d ":" -f1 | tr "
" " ")
if [ -z "$arg_field_line_nums" ]; then
echo -e "error: "$arg_field": can not find argument field"
exit $ERROR_NUM
fi
echo "matched argument field in line: $arg_field_line_nums"
# the $arg_field_line_num must in the interval ($arg_unit_line_num, $next_neighbour_unit_line_num)
for arg_field_line_num in $arg_field_line_nums
do
if [ $arg_field_line_num -gt $arg_unit_line_num -a $arg_field_line_num -lt $next_neighbour_unit_line_num ]; then
echo "find argument field in line: $arg_field_line_num"
return $arg_field_line_num
fi
done
# if not return in for-loop, the arg_field_line_num is not in the interval ($arg_unit_line_num, $next_neighbour_unit_line_num)
echo -e "the argument field is not in the argument unit interval"
exit $ERROR_NUM
}
while [ "$1" ]
do
# Check if the separator "=" that separate the argument name and argument value exists
equal_symbol=$(echo $1 | grep "=")
if [ -z "$equal_symbol" ]; then
echo -e "error: "$1": argument has no "=""
exit $ERROR_NUM
fi
# Check if argument name and argument value exist
arg_name=$(echo $1 | cut -d "=" -f 1)
arg_value=$(echo $1 | cut -d "=" -f 2)
if [ -z "$arg_name" -o -z "$arg_value" ]; then
echo -e "error: "$1": argument has no name or value around "=""
exit $ERROR_NUM
fi
# Get the line number of the argument from CONFIG_FILE
get_line_num $arg_name
args_line_num=$?
# use sed change the argument line
arg_field=$(echo $arg_name | cut -d "-" -f 2)
sed -i "${args_line_num}c $arg_field=$arg_value" $CONFIG_FILE
new_line=$(sed -n "${args_line_num}p" $CONFIG_FILE)
echo "the argument has been changed: $new_line"
shift 1
done
用户通过以下命令修改配置：
./modify_config_file BUSINESS-port=8888
输出以下：
argument unit interval: (8, 11)
matched argument field in line: 6 9
find argument field in line: 9
the argument has been changed: port=8888
其中，第1行表示找到BUSINESS这个unit所在的行号区间，注意是开区间；第2行表示所有匹配到field行号，由于可能多个unit中有相同的field；第3行表示终究落入unit区间的field行号；第4行表示所在行修改后的结果。
另外，用户输入不符合格式是很有可能，针对以下几种毛病都会报告并且定位：
1. ./modify_config_file BUSINESS
error: "BUSINESS": argument has no "="
2. ./modify_config_file BUSINESS=
error: "BUSINESS=": argument has no name or value around "="
3. ./modify_config_file BUSINESS=8888
error: "BUSINESS": argument name has no separator "-" that separate the argument unit and argument field
4. ./modify_config_file BUSINESS-=8888
error: "BUSINESS-": argument name has no argument unit or argument field around "-"
5. ./modify_config_file BUSINESS-por=8888
argument unit interval: (8, 11)
error: "por": can not find argument field
6. ./modify_config_file BUSINE-port=8888
error: "BUSINE": can not find argument unit
如果要利用到其它的配置文件，需要在脚本中修改配置文件所在路径与文件名：
MY_HOME="/home/weizheng/10⑶0-yg/yg-soft"
CONFIG_FILE="$MY_HOME/config.ini"
生活不易，码农辛苦
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