screen命令

可以用这个命令来实现程序的后台运行，这样即使服务器连接断了，程序也能继续运行。

[root@localhost ~]# screen //第一次使用需要安装
-bash: screen: command not found
[root@localhost ~]# yum install screen //使用yum安装
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile

 * base: mirrors.aliyun.com
 * extras: mirrors.ustc.edu.cn
 * updates: mirrors.ustc.edu.cn
   Resolving Dependencies
   --> Running transaction check
   ---> Package screen.x86_64 0:4.1.0-0.27.20120314git3c2946.el7_9 will be installed
   --> Finished Dependency Resolution

Dependencies Resolved

=================================================================================================

 Package        Arch           Version                                     Repository       Size
=================================================================================================

Installing:
 screen         x86_64         4.1.0-0.27.20120314git3c2946.el7_9          updates         553 k

Transaction Summary
=================================================================================================

Install  1 Package

Total download size: 553 k
Installed size: 914 k
Is this ok [y/d/N]: y
Downloading packages:
screen-4.1.0-0.27.20120314git3c2946.el7_9.x86_64.rpm                      | 553 kB  00:00:02     
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  Installing : screen-4.1.0-0.27.20120314git3c2946.el7_9.x86_64                              1/1 
  Verifying  : screen-4.1.0-0.27.20120314git3c2946.el7_9.x86_64                              1/1 

Installed:
  screen.x86_64 0:4.1.0-0.27.20120314git3c2946.el7_9                                             

Complete!
[root@localhost ~]# 

Screen命令参数：

-A -[r|R]          将所有的视窗都调整为目前终端机的大小。
-c filename        用指定的filename文件替代screen的配置文件’.screenrc’.
-d [pid.tty.host]  断开screen进程(使用该命令时，screen的状态一定要是Attached，也就是说有用户连在screen里)。一般进程的名字是以pid.tty.host这种形式表示(用screen -list命令可以看出状态)。
-D [pid.tty.host]  与-d命令实现一样的功能，区别就是如果执行成功，会踢掉原来在screen里的用户并让他logout。
-h <行数> 　       指定视窗的缓冲区行数。

-ls或–list        显示目前所有的screen作业。
-m                    即使目前已在作业中的screen作业，仍强制建立新的screen作业。
-p number or name  预先选择一个窗口。
-r [pid.tty.host]  恢复离线的screen进程，如果有多个断开的进程，需要指定[pid.tty.host]
-R                      先试图恢复离线的作业。若找不到离线的作业，即建立新的screen作业。
-s shell             指定建立新视窗时，所要执行的shell。
-S <作业名称>  指定screen作业的名称。(用来替代[pid.tty.host]的命名方式,可以简化操作).
-v                     显示版本信息。
-wipe                检查目前所有的screen作业，并删除已经无法使用的screen作业。
-x                     恢复之前离线的screen作业。

screen命令：
1、创建新screen会话，用参数-S

screen –S [SESSION]
[root@localhost ~]# who
root     pts/0        2024-01-09 19:34 (192.168.198.1)//当前是pts/0
[root@localhost ~]# screen -S test /创建第一个终端会话
[root@localhost ~]# who
root     pts/1        2024-01-09 19:38 (192.168.198.1:S.0) //当前是pts/1
[root@localhost ~]# screen -ls //显示所有已经打开的screen会话
There is a screen on:
        8144.test       (Attached)
1 Socket in /var/run/screen/S-root.

[root@localhost ~]# screen -S test2 /创建第二个终端会话
[root@localhost ~]# who
root     pts/2        2024-01-09 19:39 (192:S.0)
[root@localhost ~]# screen -ls ///显示所有已经打开的screen会话
There are screens on:
        8157.test2      (Attached)
        8144.test       (Attached)
2 Sockets in /var/run/screen/S-root.

[root@localhost ~]# 

加入screen会话

screen –x [SESSION]

显示所有已经打开的screen会话

screen -ls

2、恢复某screen会话,使用参数-r或者-x，如果会话是(Attached)状态，需要加-d选项，表示断开screen进程，因为1个screen无法同时打开2次。

screen -r [SESSION]
[root@localhost ~]# screen -ls
There are screens on:
        8157.test2      (Attached)
        8144.test       (Attached)
2 Sockets in /var/run/screen/S-root.

[root@localhost ~]# screen -r test
There are screens on:
        8157.test2      (Attached)
        8144.test       (Attached)
There is no screen to be resumed matching test.//无法进入
[root@localhost ~]# screen -dr test //加-d进入成功
[root@localhost ~]# screen -ls
There are screens on:
        8157.test2      (Attached)
        8144.test       (Attached)
2 Sockets in /var/run/screen/S-root.

[root@localhost ~]# who am i
root     pts/2        2024-01-09 19:39 (192:S.0)
[root@localhost ~]#

退出并关闭screen会话

Exit
[root@localhost ~]# screen -ls
There are screens on:
        8157.test2      (Attached)
        8144.test       (Attached)
2 Sockets in /var/run/screen/S-root.

[root@localhost ~]# who am i
root     pts/2        2024-01-09 19:39 (192:S.0)
[root@localhost ~]# exit
exit

[screen is terminating]
[root@localhost ~]# screen -ls //只剩下一个，退出成功
There is a screen on:
        8144.test       (Attached)
1 Socket in /var/run/screen/S-root.

[root@localhost ~]# 

3、退出当前screen会话。

Ctrl+D  # 在当前screen下，输入Ctrl+D，删除该screen
Ctrl+A，Ctrl+D  # 在当前screen下，输入先后Ctrl+A，Ctrl+D，退出该screen
[detached from 8144.test] //退出成功
[root@localhost ~]# 
[root@localhost ~]# screen -ls
There is a screen on:
        8144.test       (Detached)
1 Socket in /var/run/screen/S-root.

[root@localhost ~]# screen -r test //进入会话，(Detached)状态只要-r参数或者使用-x参数
[root@localhost ~]# who
root     pts/1        2024-01-09 19:38 (192.168.198.1:S.0)
[root@localhost ~]# screen -ls
There is a screen on:
        8144.test       (Attached)
1 Socket in /var/run/screen/S-root.

[root@localhost ~]#