Linux Bash 脚本中的变量，使其保持上次运行时的值
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Variable in Bash Script that keeps it value from the last time running
提问by Ferenjito
Can I create a Bash script with persistent variable-values?
我可以创建具有持久变量值的 Bash 脚本吗？
For example, I initialize a variable with 0 when the script runs for the first time (during a specific time limit), and the variable increases automatically with every time the script is running.
例如，我在脚本第一次运行时（在特定时间限制内）将变量初始化为 0，并且每次脚本运行时变量都会自动增加。
采纳答案by dldnh
you can't, but you can use a file to do it
你不能，但你可以使用一个文件来做到这一点
#!/bin/sh
# if we don't have a file, start at zero
if [ ! -f "/tmp/value.dat" ] ; then
value=0
# otherwise read the value from the file
else
value=`cat /tmp/value.dat`
fi
# increment the value
value=`expr ${value} + 1`
# show it to the user
echo "value: ${value}"
# and save it for next time
echo "${value}" > /tmp/value.dat
回答by Gareth Davis
I'm afraid you have to save the state in a file somewhere. The trick is to put it somewhere the user will be able to write to.
恐怕您必须将状态保存在某个文件中。诀窍是把它放在用户可以写入的地方。
yourscriptvar=0
if [ -e "$HOME/.yourscriptvar" ] ; then
yourscriptvar=$(cat "$HOME/.yourscriptvar")
fi
# do something in your script
#save it output the file
echo $yourscriptvar > "$HOME/.yourscriptvar"
回答by Arturo Herrero
I had the same problem a few days ago and I've written my own tool to do the work because there is not other way to do something similar.
几天前我遇到了同样的问题，我编写了自己的工具来完成这项工作，因为没有其他方法可以做类似的事情。
gvaris a pure Bash key-value store where each user has a different collection of data. The records are stored in the user's home directory.
gvar是一个纯 Bash 键值存储，其中每个用户都有不同的数据集合。记录存储在用户的主目录中。
Here it is the most interesting functions from the source code:
这是源代码中最有趣的函数：
get_variable() {
cat $FILE | grep -w | cut -d'=' -f2
}
set_variable() {
echo = >> $FILE
}
remove_variable() {
sed -i.bak "/^=/d" $FILE
}
