GNU Screen

来自 Arch Linux 中文维基

GNU Screen 是一个全屏窗口管理器,它在多个进程(通常是交互式 shell)之间复用一个物理终端。Screen 中运行的程序在其窗口当前不可见时仍可继续运行,甚至在整个屏幕会话从用户终端分离时也是如此。

有关功能之描述,参阅官方概述 GNU Screen 手册

安装[编辑 | 编辑源代码]

安装 screen 软件包。

用法[编辑 | 编辑源代码]

输入命令时按下 "转义键 "Ctrl+a,然后进行键绑定。

有些用户认为默认的转义键 Ctrl+a 不方便。可以按照 #更改转义键中的说明,将转义键更改为其他键。

常用命令[编辑 | 编辑源代码]

  • Ctrl+a ? 显示命令及其默认值
  • Ctrl+a : 进入屏幕命令提示符
  • Ctrl+a " 窗口列表
  • Ctrl+a 0 打开窗口 0
  • Ctrl+a A 命名当前窗口
  • Ctrl+a a 发送到 Ctrl+a 当前窗口
  • Ctrl+a c 创建一个新窗口(带 shell)
  • Ctrl+a S 将当前区域水平拆分为两个区域
  • Ctrl+a | 将当前区域垂直拆分为两个区域
  • Ctrl+a tab 将输入焦点切换到下一个区域
  • Ctrl+a Ctrl+a 在当前区域和上一个区域之间切换
  • Ctrl+a Esc 进入复制模式(使用 Enter 选择文本范围)
  • Ctrl+a ] 粘贴文本
  • Ctrl+a Q 关闭除当前区域之外的所有区域
  • Ctrl+a X 关闭当前区域
  • Ctrl+a d 脱离当前 screen 会话,让其继续运行。使用 screen -r 恢复

命令提示符命令[编辑 | 编辑源代码]

  • Ctrl+a :quit 关闭所有窗口并关闭屏幕会话

Closes all windows and closes screen session

  • Ctrl+a :source ~/.screenrc 重载 screenrc 配置文件(也可使用 /etc/screenrc

命名会话[编辑 | 编辑源代码]

要创建命名会话,请使用以下命令运行 screen:

$ screen -S session_name

要(重新)命名现有会话,请在屏幕运行时运行以下命令:

Ctrl+a :sessionname session_name

打印标识屏幕会话的 pid.tty.host 字符串列表:

$ screen -list

要附加到已命名的屏幕会话,请运行此命令:

$ screen -x session_name

$ screen -r session_name

自定义屏幕[编辑 | 编辑源代码]

You can modify the default settings for Screen according to your preference either through a personal .screenrc file which contains commands to be executed at startup (e.g. ~/.screenrc) or on the fly in command mode (e.g. Ctrl+a :vbell off).

Tips and tricks[编辑 | 编辑源代码]

Autostart with systemd[编辑 | 编辑源代码]

This service autostarts screen for the specified user (e.g. systemctl enable screen@florian). Running this as a system unit is important, because systemd --user instance is not guaranteed to be running and will be killed when the last session for given the user is closed.

/etc/systemd/system/screen@.service
[Unit]
Description=screen
After=network.target

[Service]
Type=simple
User=%i
ExecStart=/usr/bin/screen -DmS autoscreen
ExecStop=/usr/bin/screen -S autoscreen -X quit

[Install]
WantedBy=multi-user.target

Change the escape key[编辑 | 编辑源代码]

It can be a good idea to change the default escape key, not only because "a" is usually typed with the left pinky, but also because Ctrl+a is mapped to the common command beginning-of-line in GNU Readline and Bash-like shells.

The escape key can be changed with the escape option in ~/.screenrc, or the -e option to screen.

For example, if you find that you rarely type Ctrl+j in your shell or editor, you could use escape ^Jj to set the escape key to Ctrl+j. The second "j" means that a literal Ctrl+j can be sent to the terminal via the sequence Ctrl+j j. For Dvorak keyboard users, Ctrl+t (escape ^Tt) might be more convenient.

More exotic options include escape `` which sets the escape key to `, or escape ^^^ which sets it to Ctrl+^.

The escape key is also called the "command character" in Screen documentation.

Start at window 1[编辑 | 编辑源代码]

By default, the first screen window is 0. If you would rather never have a window 0 and start instead with 1, add the following lines on your configuration:

~/.screenrc
bind c screen 1
bind ^c screen 1
bind 0 select 10                                                            
screen 1

Nested Screen Sessions[编辑 | 编辑源代码]

It is possible to get stuck in a nested screen session. A common scenario: you start an SSH session from within a screen session. Within the SSH session, you start screen. By default, the outer screen session that was launched first responds to Ctrl+a commands. To send a command to the inner screen session, use Ctrl+a a, followed by your command. For example:

  • Ctrl+a a d Detaches the inner screen session.
  • Ctrl+a a K Kills the inner screen session.

Start Screen on every shell[编辑 | 编辑源代码]

For Bash and Zsh, add the following snippet to your .bashrc or .zshrc before your aliases:

~/.bashrc or ~/.zshrc
if [[ -z "$STY" ]]; then
   screen -xRR session_name
fi

Use 256 colors[编辑 | 编辑源代码]

本文内容或本节内容已经过期。

原因: screen 4.4 sets $TERM to screen.$TERM, although the manual says something different. There should be no need to modify it in ~/.screenrc. (在Talk:GNU Screen讨论)

By default, Screen uses an 8-color terminal emulator. To enable more colors, you need to be using a terminal that supports them and set the correct term value. This will use terminfo to describe how the ANSI escape codes will be interpreted. An entry in the terminfo database structure must exist, ncurses provides many common descriptions stored under /usr/share/terminfo/.

First try the generic value:

~/.screenrc
term screen-256color

If that does not work, try setting it based on your terminal. When using xterm-based terminal:

~/.screenrc
term xterm-256color

When using rxvt-unicode:

~/.screenrc
term rxvt-unicode-256color
注意: /usr/share/terminfo/r/rxvt-unicode-256color is provided by rxvt-unicode-terminfo, which is installed as a dependency of rxvt-unicode. However, if you log into a server via SSH and run screen there, this terminfo file might not be available on the server. In this case it is recommended to copy /usr/share/terminfo/r/rxvt-unicode-256color on the server, it can be saved in ~/.terminfo/.

As a last resort, try setting termcapinfo instead:

~/.screenrc
attrcolor b ".I"    # allow bold colors - necessary for some reason
termcapinfo xterm 'Co#256:AB=\E[48;5;%dm:AF=\E[38;5;%dm'   # tell screen how to set colors. AB = background, AF=foreground
defbce on    # use current bg color for erased chars

Informative statusbar[编辑 | 编辑源代码]

The default statusbar may be a little lacking. You may find this one more helpful:

~/.screenrc
hardstatus off
hardstatus alwayslastline
hardstatus string '%{= kG}[ %{G}%H %{g}][%= %{= kw}%?%-Lw%?%{r}(%{W}%n*%f%t%?(%u)%?%{r})%{w}%?%+Lw%?%?%= %{g}][%{B} %m-%d %{W} %c %{g}]'

Another possibility, taken from frodfrog's blog[失效链接 2023-04-23 ⓘ] is:

~/.screenrc
hardstatus alwayslastline '%{= G}[ %{G}%H %{g}][%= %{= w}%?%-Lw%?%{= R}%n*%f %t%?%{= R}(%u)%?%{= w}%+Lw%?%= %{= g}][ %{y}Load: %l %{g}][%{B}%Y-%m-%d %{W}%c:%s %{g}]'

As of Screen v5 (master branch currently) the escape codes have changed, you could use this instead:

~/.screenrc
truecolors on
hardstatus off
backtick 0 5 5 "/bin/date" '+%Y-%m-%d'
backtick 1 5 5 "/bin/date" '+%H:%M'
hardstatus alwayslastline '%{#00ff00}[ %H ][%{#ffffff}%= %{7}%?%-Lw%?%{1;0}%{1}(%{15}%n%f%t%?(%u)%?%{1;0}%{1})%{7}%?%+Lw%?%? %=%{#00ff00}][ %{#00a5ff}%{6}%0` %{#ffffff}%{7}%1`%{#00ff00} ]'

statusbar at top:

~/.screenrc
hardstatus firstline 

Turn welcome message off[编辑 | 编辑源代码]

~/.screenrc
startup_message off

Turn your hardstatus line into a dynamic urxvt|xterm|aterm window title[编辑 | 编辑源代码]

This one is pretty simple; just switch your current hardstatus line into a caption line with notification, and edit accordingly:

~/.screenrc
backtick 1 5 5 true
termcapinfo rxvt* 'hs:ts=\E]2;:fs=\007:ds=\E]2;\007'
hardstatus string "screen (%n: %t)"
caption string "%{= kw}%Y-%m-%d;%c %{= kw}%-Lw%{= kG}%{+b}[%n %t]%{-b}%{= kw}%+Lw%1`"
caption always

This will give you something like screen (0 bash) in the title of your terminal emulator. The caption supplies the date, current time, and colorizes your screen window collection.

Use X scrolling mechanism[编辑 | 编辑源代码]

The scroll buffer of GNU Screen can be accessed with Ctrl+a [. However, this is very inconvenient. To use the scroll bar of e.g. xterm or Konsole, add the following line [1]:

~/.screenrc
termcapinfo xterm*|rxvt*|kterm*|Eterm* ti@:te@

Attach an existing running program to screen[编辑 | 编辑源代码]

If you started a program outside Screen, but now you would like it to be inside, you can use reptyr to reparent the process from its current TTY to one inside screen.

Install the reptyr package.

Get the PID of the process (you can use ps ax for that). Now just enter the PID as argument to reptyr inside a screen window.

$ reptyr pid

Setting a different bash prompt while in screen[编辑 | 编辑源代码]

If you want a different bash prompt when in a screen session, add the following to your .bashrc[2]:

if [ -z $STY ]
then
        PS1="YOUR REGULAR PROMPT"
else  
        PS1="YOUR SCREEN PROMPT"
fi

Turn off visual bell[编辑 | 编辑源代码]

With this setting, Screen will not make an ugly screen flash instead of a bell sound.

~/.screenrc
vbell off

Getting rid of the vertical and horizontal bars[编辑 | 编辑源代码]

To get rid of the vertical bars:

$ ~/.screenrc
rendition so =00

To hide the horizontal bar, set the back and foreground color to default (d) and display a blank (" "):

~/.screenrc
caption string "%{03} "

If this does not work, try caption string "%{00} " instead. For the default caption in black and white, use caption string "%{00}%3n %t".

Troubleshooting[编辑 | 编辑源代码]

Fix for residual editor text[编辑 | 编辑源代码]

When you open a text editor like nano in screen and then close it, the text may stay visible in your terminal. To fix this, put the following:

~/.screenrc
altscreen on

Fix for Name column in windowlist only show "bash"[编辑 | 编辑源代码]

这篇文章的某些内容需要扩充。

原因: Explain what does the command do. (在 Talk:GNU Screen 中讨论)

Add following to ~/.screenrc:

~/.screenrc
windowlist string "%4n %h%=%f"

See also[编辑 | 编辑源代码]