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This article mainly introduces how to achieve a permanent cycle in Linux's bash, with a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let the editor take you to understand it.

There are many ways to loop forever (or until you decide to stop) in Linux, which you can do on the command line or in a script.

The for and while commands make this very easy. There are only a few things to keep in mind about the corresponding grammar and strategy.

Use while

One of the simplest permanent loops is to use the while command, followed by a conditional true. You don't have to use logic like while [1-eq 1] or similar tests. The while true test indicates that the loop will run until you use CTRL-C to stop the loop, close the terminal window, or log out. This is an example:

$while true > do > echo Keep running > sleep 3 > doneKeep runningKeep runningKeep running ^ C

You can also use while: do the same thing. The key here is that success is always returned, so like while true, this test never fails, and the loop continues to run:

$while: > do > echo Keep running > sleep 3 > doneKeep runningKeep running ^ C

If you insert an infinite loop into the script and want to remind the user of how to exit the script, you can use the echo command to add a prompt:

While: do echo Keep running echo "Press CTRL+C to exit" sleep 1done uses for

The for command also provides an easy way to loop forever. Although not as obvious as while true, the syntax is quite simple. You just need to replace the parameter in a bounded loop, which usually looks like "c increments from 1 to 5":

Why does $for ((clocked 1; c do > echo Keep running > echo "Press CTRL+C to exit" > sleep 2 > doneKeep your spirits upKeep your spirits upKeep your spirits up) loop forever?

In reality, you don't want to cycle forever, but it's not uncommon to keep running until you want to go home, finish your work, or have a problem. Any loop constructed as an infinite loop can be set to exit according to a variety of circumstances.

The script will process the data until 5 p.m., or when it is found to be above 5 p.m. For the first time:

#! / bin/bash while truedo if [`date +% H`-ge 17]; then exit # exit script fi echo keep running ~ / bin/process_data # do some workdone

If you want to exit the loop instead of the script, use the break command instead of exit.

#! / bin/bash while truedo if [`date +% H`-ge 17]; then break # exit loop fi echo keep running ~ / bin/process_datadone … Run other commands here... Thank you for reading this article carefully. I hope the article "how to achieve a permanent cycle in Linux bash" shared by the editor will be helpful to everyone. At the same time, I also hope that you will support and pay attention to the industry information channel. More related knowledge is waiting for you to learn!

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