A program is always executed in the LINUX background.

In the LINUX background, you can always run a program using the nohup command to make the Linux program always run Unix/Linux in the background and generally want to run a program in the background, many of them use & to make the program run automatically at the end of the program. For example, we want to run mysql in the background:/usr/local/mysql/bin/mysqld_safe -- user = mysql & but many of our programs do not support daemon like mysqld, maybe our program is just a common program. Generally, even if this program is used and ended, if the terminal is closed, the program will be closed. To be able to run in the background, we need to use the nohup command. For example, we have a start command. sh needs to run in the background, and you want to continue running in the background, then use nohup: nohup/root/start. sh & press enter in shell and the prompt is: [~] $ Appending output to nohup. out the standard output of the original program is automatically changed to the nohup. out file in the current directory, which plays the role of log. But sometimes there is a problem at this step. When the terminal is closed, the process will be automatically closed. Check nohup. out to see that the service will be automatically closed when the terminal is closed. After consulting with the red-flag Linux engineer, he could not solve the problem. After executing the command on my terminal, the process he started was still running after the terminal was closed. During the second demonstration to me, I found that I had a different detail with him when operating the terminal: when the shell prompts that nohup is successful, you also need to press any key on the terminal to return to the shell input command window, and then enter exit in the shell to exit the terminal; however, I click the close program button to close the terminal every time the nohup operation is successful .. Therefore, the session corresponding to the command will be disconnected at this time, and the process corresponding to nohup will be notified and shutdown will be required together. I did not notice the details, so I recorded them here. Appendix: nohup command reference nohup command purpose: run the command without hanging up. Syntax: nohup Command [Arg...] [&] Description: The nohup Command runs the Command specified by the Command parameter and any relevant Arg parameter, ignoring all SIGHUP signals. After logging out, run the nohup command to run the program in the background. To run the nohup command in the background, add the & (symbol indicating "and") to the end of the command. Whether or not the output of the nohup command is redirected to the terminal, the output will be appended to the nohup. out file in the current directory. If the nohup. out file in the current directory cannot be written, the output will be redirected to the $ HOME/nohup. out file. If no file can be created or opened for append, the Command specified by the Command Parameter cannot be called. If a standard error is a terminal, write the specified command to all outputs of the standard error as the standard output and redirect it to the same file descriptor. Exit status: This Command returns the following export value: 126 can be searched but cannot call the Command specified by the Command parameter. 127 The nohup Command has an error or cannot find the Command specified by the Command parameter. Otherwise, the exit status of the nohup Command is the exit status of the Command specified by the Command parameter. Nohup command and its output file nohup command: If you are running a process and you think the process will not end when you exit the account, you can use the nohup command. This command can continue running the corresponding process after you exit the account/Close the terminal. Nohup means not to suspend (n ohang up ). The general form of this command is: nohup command & use nohup command to submit a job. If you use the nohup command to submit a job, by default, all the output of this job is redirected to a job named nohup. unless the output file: nohup command> myout is specified. file 2> & 1 & in the preceding example, the output is redirected to myout. file. Use jobs to view tasks. Disable using fg % n. There are also two commonly used ftp tools ncftpget and ncftpput, which can be used to upload and download files in the background through ftp, so that you can use these commands to upload and download files in the background.