有時候會有這樣的問題，當在公司服務器上打開了一個終端，做了很多事情，或正開著某個服務程序,下班回家了。
突然有事需要接入到服務器，如果用 ssh 連入，默認是一個新的終端，並不會打開你之前在公司的那個會話。而這時又需要繼續在原來那個會話下操作。
今天發現 linux 下有一個 screen 命令，很有用. 在開啟終端後，先運行一下 screen ,這樣後續的操作都會被綁定到這個 screen 上。 而且可以在其它ssh 會話上使用 screen 命令打開舊的會話 ,繼續未完成的事,甚至可以多個ssh連入同時共享一個會話，輸入的命令會在所有共享ssh客戶端同時顯示，非常有趣.
例：
A連上服務器，並運行 screen
ssh user@server
screen
B連上服務器，打開A的會話
ssh user@server
screen -ls # 查看會話id
screen -rx xxxxx #打開指定的會話.
更多請查看 screen 的幫助:
Use: screen [-opts] [cmd [args]]
or: screen -r [host.tty]
Options:
-a Force all capabilities into each window's termcap.
-A -[r|R] Adapt all windows to the new display width & height.
-c file Read configuration file instead of '.screenrc'.
-d (-r) Detach the elsewhere running screen (and reattach here).
-dmS name Start as daemon: Screen session in detached mode.
-D (-r) Detach and logout remote (and reattach here).
-D -RR Do whatever is needed to get a screen session.
-e xy Change command characters.
-f Flow control on, -fn = off, -fa = auto.
-h lines Set the size of the scrollback history buffer.
-i Interrupt output sooner when flow control is on.
-l Login mode on (update /var/run/utmp), -ln = off.
-list or -ls. Do nothing, just list our SockDir.
-L Turn on output logging.
-m ignore $STY variable, do create a new screen session.
-O Choose optimal output rather than exact vt100 emulation.
-p window Preselect the named window if it exists.
-q Quiet startup. Exits with non-zero return code if unsuccessful.
-r Reattach to a detached screen process.
-R Reattach if possible, otherwise start a new session.
-s shell Shell to execute rather than $SHELL.
-S sockname Name this session <pid>.sockname instead of <pid>.<tty>.<host>.
-t title Set title. (window's name).
-T term Use term as $TERM for windows, rather than "screen".
-U Tell screen to use UTF-8 encoding.
-v Print "Screen version 4.00.03jw4 (FAU) 2-May-06".
-wipe Do nothing, just clean up SockDir.
-x Attach to a not detached screen. (Multi display mode).
-X Execute <cmd> as a screen command in the specified session.
