这是一个后续的问题,你如何使用ssh在一个shell脚本?的问题。如果我想在远程机器上执行在后台运行的命令,如何返回ssh命令?当我试图在命令末尾只包含&号时,它就挂起了。命令的确切形式如下所示:

ssh user@target "cd /some/directory; program-to-execute &"

什么好主意吗?需要注意的一件事是,登录到目标机器总是产生一个文本横幅,我设置了SSH密钥,所以不需要密码。


当前回答

If you run remote command without allocating tty, redirect stdout/stderr works, nohup is not necessary. ssh user@host 'background command &>/dev/null &' If you use -t to allocate tty to run interactive command along with background command, and background command is the last command, like this: ssh -t user@host 'bash -c "interactive command; nohup backgroud command &>/dev/null &"' It's possible that background command doesn't actually start. There's race here: bash exits after nohup starts. As a session leader, bash exit results in HUP signal sent to nohup process. nohup ignores HUP signal. If 1 completes before 2, the nohup process will exit and won't start the background command at all. We need to wait nohup start the background command. A simple workaroung is to just add a sleep: ssh -t user@host 'bash -c "interactive command; nohup backgroud command &>/dev/null & sleep 1"'

这个问题在几年前就被提出和回答了,我不知道openssh的行为从那时起是否发生了变化。我在测试: OpenSSH_8.6p1, OpenSSL 1.1.1g FIPS 21 Apr 2020

其他回答

最快和最简单的方法是使用'at'命令:

ssh user@target "at now -f /home/foo.sh"

fd的重定向

输出需要用&>/dev/null重定向,它将stderr和stdout重定向到/dev/null,是>/dev/null 2>/dev/null或>/dev/null 2>&1的同义词。

偏执狂

最好的方法是使用sh -c '((command) &)',其中command是任何东西。

ssh askapache 'sh -c "( ( nohup chown -R ask:ask /www/askapache.com &>/dev/null ) & )"'

Nohup壳

你也可以使用nohup直接启动shell:

ssh askapache 'nohup sh -c "( ( chown -R ask:ask /www/askapache.com &>/dev/null ) & )"'

漂亮的发射

另一个技巧是使用nice来启动命令/shell:

ssh askapache 'nice -n 19 sh -c "( ( nohup chown -R ask:ask /www/askapache.com &>/dev/null ) & )"'

我认为这是你需要的: 首先,您需要在您的机器上安装sshpass。 然后你可以编写自己的脚本:

while read pass port user ip; do
sshpass -p$pass ssh -p $port $user@$ip <<ENDSSH1
    COMMAND 1
    .
    .
    .
    COMMAND n
ENDSSH1
done <<____HERE
    PASS    PORT    USER    IP
      .      .       .       .
      .      .       .       .
      .      .       .       .
    PASS    PORT    USER    IP    
____HERE

没有nohup你也可以做到:

ssh user@host 'myprogram >out.log 2>err.log &'

If you run remote command without allocating tty, redirect stdout/stderr works, nohup is not necessary. ssh user@host 'background command &>/dev/null &' If you use -t to allocate tty to run interactive command along with background command, and background command is the last command, like this: ssh -t user@host 'bash -c "interactive command; nohup backgroud command &>/dev/null &"' It's possible that background command doesn't actually start. There's race here: bash exits after nohup starts. As a session leader, bash exit results in HUP signal sent to nohup process. nohup ignores HUP signal. If 1 completes before 2, the nohup process will exit and won't start the background command at all. We need to wait nohup start the background command. A simple workaroung is to just add a sleep: ssh -t user@host 'bash -c "interactive command; nohup backgroud command &>/dev/null & sleep 1"'

这个问题在几年前就被提出和回答了,我不知道openssh的行为从那时起是否发生了变化。我在测试: OpenSSH_8.6p1, OpenSSL 1.1.1g FIPS 21 Apr 2020