====== Command-Line Options ======

Screen has the following command-line options:

  ; ''-a''  : include  //all//  capabilities  (with some minor exceptions) in each window's termcap, even if ''screen'' must redraw parts of  the  display  in  order  to implement a function.
  ; ''-A''  : Adapt  the  sizes of all windows to the size of the current terminal.  By default, ''screen'' tries to restore its old window sizes when  attaching  to resizable  terminals  (those with "WS" in its description, e.g. ''suncmd'' or some ''xterm'').
  ; ''-c'' //file// : override the default configuration file from "$HOME/.screenrc" to //file//.
  ; ''-d''|''-D'' [//pid//''.''//tty//''.''//host//] : does not start ''screen'', but detaches the elsewhere running ''screen'' session.  It has the same effect as typing "''[[commands:detach|C-a d]]''" from ''screen'''s controlling terminal. ''-D'' is the equivalent to the power detach key.  If no session can  be detached,  this  option  is ignored. In combination with the ''-r''/''-R'' option more powerful effects can be achieved:
    * ''-d -r'' - Reattach a session and if necessary detach it first.
    * ''-d -R'' - Reattach a session and if necessary detach or even create it first.
    * ''-d -RR'' - Reattach a session and if necessary detach or create it. Use the first session if more than one session is available.
    * ''-D -r'' - Reattach a session. If necessary detach and logout remotely first.
    * ''-D -R'' - Attach  here  and  now. In detail this means: If a session is running, then reattach. If necessary detach and logout remotely first.   If  it was  not  running  create it and notify the user. This is the author's favorite.
    * ''-D -RR'' - Attach here and now. Whatever that means, just do it.
Note: It is always a good idea to check the status of  your  sessions  by means of "''screen -list''".
  ; ''-e'' //xy// : specifies  the  command  character to be //x// and the character generating a literal command character to //y// (when typed after the command  character).  The  default  is  "''C-a''" and '''a''', which can be specified as "''-e^Aa''".  When creating a screen session, this option sets the default  command  character. In a multiuser session all users added will start off with this command character.  But when attaching to an already  running  session,  this option  changes  only  the command character of the attaching user.  This option is equivalent to  either  the  commands  "[[commands:defescape]]"  or  "[[commands:escape]]" respectively.
  ; ''-f'', ''-fn'', and ''-fa'' : turns flow-control on, off, or "automatic switching mode".  This can also be defined through the "''[[commands:defflow]]''" .screenrc command.
  ; ''-h'' //num// : Specifies the history scrollback buffer to be //num// lines high.
  ; ''-i'' : will cause the interrupt key (usually C-c) to interrupt the display immediately when flow-control is on.  See the "''[[commands:defflow]]''" .screenrc command for details.  The use of this option is discouraged.
  ; ''-l'' and ''-ln'' : turns login mode on or off (for /var/run/utmp updating).  This  can  also be defined through the "''[[commands:deflogin]]''" .screenrc command.
  ; ''-ls'' and ''-list'' : does not start ''screen'', but prints a list of //pid//.//tty//.//host// strings and creation timestamps  identifying  your  ''screen''  sessions.   Sessions  marked 'detached'  can  be resumed with "''screen -r''". Those marked 'attached' are running and have a controlling terminal. If the session runs in multiuser mode,  it is marked 'multi'. Sessions marked as 'unreachable' either live on a different host or are 'dead'.  An unreachable session is  considered dead,  when  its  name  matches either the name of the local host, or the specified parameter, if any.  See the ''-r'' flag for a  description of how  to construct  matches.   Sessions  marked  as  'dead'  should  be thoroughly checked and removed.  Ask your system administrator if you are not  sure.  Remove sessions with the ''-wipe'' option.
  ; ''-L''  : tells ''screen'' to turn on automatic output logging for the windows.
  ; ''-m''  : causes  ''screen''  to ignore the $STY environment variable. With "''screen -m''", creation of a new session  is  enforced,  regardless  whether  ''screen''  is called from within another ''screen'' session or not. This flag has a special meaning in connection with the ''-d'' option:
    * ''-d -m'' - Start ''screen'' in "detached"  mode.  This  creates  a  new  session  but doesn't attach to it. This is useful for system startup scripts.
    * ''-D -m'' - This  also  starts  ''screen''  in "detached" mode, but doesn't fork a new process. The command exits if the session terminates.
  ; ''-O''  : selects a more optimal output mode for your  terminal  rather  than  true VT100  emulation (only affects auto-margin terminals without 'LP').  This can also be set in your .screenrc by specifying 'OP' in a "''[[commands:termcap]]''"  command.
  ; ''-p'' //number_or_name// : Preselect  a  window.  This is useful when you want to reattach to a specific window or you want to send a command via the "''-X''" option to a  specific window. As with ''screen'''s ''[[commands:select]]'' command, "-" selects the blank window. As a special case for reattach, "=" brings up the ''[[commands:windowlist]]'' on  the blank window.
  ; ''-q''  : Suppress  printing  of error messages. In combination with "''-ls''" the exit value is as follows: 9 indicates a directory without sessions.  10  indicates  a directory with running but not attachable sessions. 11 (or more) indicates 1 (or more) usable sessions.  In combination with "''-r''" the exit value  is as follows: 10 indicates that there is no session to resume. 12 (or more) indicates that there are 2 (or more) sessions to resume and you should  specify  which  one  to  choose.   In all other cases "''-q''" has no effect.
  ; ''-r'' //sessionowner//''/''[//pid//''.''//tty//''.''//host//] 
  ; ''-r'' [//pid//''.''//tty//''.''//host//] : resumes a detached ''screen'' session.  No other options (except combinations with ''-d''/''-D'') may be specified, though an optional prefix of [//pid//''.'']//tty//''.''//host// may be needed to distinguish between multiple detached  ''screen''  sessions.  The second form is used to connect to another user's ''screen'' session which runs in [[:multiuser]] mode. This indicates that ''screen'' should look  for  sessions in another user's directory. This requires setuid-root.
  ; ''-R''  : attempts  to  resume  the  youngest  (in terms of creation time) detached ''screen'' session it finds.  If successful, all other  command-line  options are  ignored.   If no detached session exists, starts a new session using the specified options, just as if ''-R'' had not been specified.  The  option is set by default if ''screen'' is run as a login-shell (actually ''screen'' uses "''-xRR''" in that case).  For combinations with the ''-d''/''-D'' option see  there.
Note: Time-based session selection is a Debian-specific addition.
  ; ''-s''  : sets  the default shell to the program specified, instead of the value in the environment variable $SHELL (or "''/bin/sh''" if not defined).  This  can also be defined through the "''[[commands:shell]]''" .screenrc command.
  ; ''-S'' //sessionname// : When  creating  a new session, this option can be used to specify a meaningful name for the session. This name identifies the session for "''screen -list''"  and  "''screen -r''"  actions. It substitutes the default [//tty//.//host//] suffix.
  ; ''-t'' //name// : sets the title (a.k.a.) for the default shell or specified program.   See also the "''[[commands:shelltitle]]''" .screenrc command.
  ; ''-U''  : Run  ''screen''  in  UTF-8  mode. This option tells ''screen'' that your terminal sends and understands UTF-8 encoded characters. It also sets the  default encoding for new windows to 'utf8'.
  ; ''-v''  : Print version number.
  ; ''-wipe'' [//match//] : does  the same as "''screen -ls''", but removes destroyed sessions instead of marking them as 'dead'.  An unreachable session is considered dead,  when its  name  matches  either  the name of the local host, or the explicitly given parameter, if any.  See the ''-r'' flag for a description how  to  construct matches.
  ; ''-x''  : Attach  to  a  not detached ''screen'' session. (Multi display mode).  ''screen'' refuses to attach  from  within  itself.   But  when  cascading  multiple ''screen''s, loops are not detected; take care.
  ; ''-X''  : Send  the  specified command to a running ''screen'' session. You can use the ''-d'' or ''-r'' option to tell ''screen'' to look  only  for  attached  or  detached ''screen''  sessions.  Note  that this command doesn't work if the session is password protected.