变量bash脚本，保持它的价值从上一次运行 [英] Variable in Bash Script that keeps it value from the last time running

问题描述

我可以创建持久的可变值的Bash脚本？

Can I create a Bash script with persistent variable-values?

例如，我一个变量初始化成0时，脚本（具体的时间限制内）首次运行，每一次自动变量增加脚本运行。

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.

推荐答案

你不能，但你可以用一个文件来做到这一点。

you can't, but you can use a file to do it

#!/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

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