Yet another GNU Screen tips & hacks page

by Artur Skonecki

Last modified:   09 February 2012

Contents:

1. how to: use "ALT + key" combination as an escape
2. how to: use the ALT key as a modifier with bind
3. how to: indicate pressed escape key in hardstatus
4. how to: tmux display-panes + swap-regions + rotate-regions in Screen
5. how to: move a process into a Screen session>
6. how to: save Screen sessions
7. how to: start a new window with the same working directory
8. how to: create a resize mode

# GNU Screen how to: use "ALT + key" combination as an escape

# Alt + space as an escape key in GNU Screen

# reset escape key to the default
escape ^Aa

# auxiliary register
register S ^A

# Alt + space produces ^A and acts as an escape key
bindkey "^[ " process S

# GNU Screen how to: use the ALT key as a modifier with bind

# ^[ escape goes first whenever one presses Alt + key
# bind ^[ to activate a command class
bind "^[" eval  "command -c class_escape" "echo \"command class: escape\""

# press Alt-? to show class_escape bindings
bind -c class_escape ? help -c class_escape 

# press Alt-r to resource .screenrc
bind -c class_escape r source "$HOME/.screenrc"

# GNU Screen how to: indicate pressed escape key in hardstatus

# invert colors when escape key active
# %{+s} is activate when %E is true

hardstatus string %?%E%{+s}%?%w

hardstatus alwayslastline

# GNU Screen how to: tmux display-panes + swap-regions + rotate-regions in Screen

< tmux display-panes       screen-display-regions >

1. >> file screen-display-regions

   - wrapper around screen-display-regions.py, it is necessary to wrap some GNU Screen scripts

2. >> file screen-display-regions.py

   - the main program

3. >> file screen-display-regions-helper

   - starts in every region, prints region numbers using "toilet --gay" and "toilet --metal" (I couldn't find anything better)

    $ git clone git://git.savannah.gnu.org/screen.git screen
    $ cd screen/src; ./autogen.sh ; autoheader ; ./configure && make
    $ sudo make install

bind n eval "screen sh -c 'sleep 0.01; screen-display-regions'" "other"

# GNU Screen how to: move a process into a Screen session

1. >> Download injcode and install it in the $PATH ( >> more about injcode ).
2. Put this script in your path:

   >> file screen-move-process - move a process between ttys

3. To move a process into Screen session:

   
       $ screen-move-process PID
       

   In the process parent shell type:

   
       $ disown
       

# GNU Screen how to: save Screen sessions

1. >> Download screen-session and install it according to instructions in INSTALL. First install screen-session itself:

   
       $ tar xf screen-session-VERSION.tar.gz
       $ cd screen-session-VERSION
       $ sudo make install
       

2. Proceed with compilation and installation of the modified GNU Screen ( build-essentials and libncurses-dev should be installed on your system ).

   
       $ cd screen-session-VERSION/screen-4.1.0
       $ ./configure
       $ make
       $ sudo make install
       

   Check whether the Screen version string matches with screen-session:

   
       $ screen --version
       Screen version 4.01.00scs_0.6.4 (screen-session project) 27-August-11
   
       $ screen-session --version
       screen-session 0.6.4 - a collection of tools for GNU Screen.
       

3. Make sure to restart running instances of Screen before using screen-session. You might want to take a look at the full screen-session documentation.
   
   To save a GNU Screen session including all its windows, layouts and processes run:

   
       $ screen-session save save_file
       

   list saved sessions:

   
       $ screen-session ls
       

   and restore ( inside another Screen session ):

   
       $ screen-session load save_file
       

   by default screen-session does not restore window numbers exactly. If you want the loaded session to reassemble closer the original, add --exact flag ( renumber all windows to make room for new ones ) or, to be even more precise, use --exact-kill flag ( which will kill all already existing windows ).

   
       $ screen-session load --exact save_file
       

   It would be very risky to let saved programs start immediately. Instead, every new window displays a prompt and waits for the confirmation.
   
   It is possible to skip this prompt entirely using "--force-start [win_nums]" option. For example, to instruct screen-session to immediately start programs in windows 1, 2, 3, 12 run:

   
       $ screen-session load --exact --force-start 1-3,12 save_file
       

# GNU Screen how to: start a new window with the same working directory

1. Create $HOME/bin/screen-in-dir and make it an executable:

   >> file screen-in-dir - starts Screen window in the same directory (this simple script is not perfect but still does its job)

2. Append to your .screenrc:

   
           #start another screen window with the same working directory
   
           bind C exec "$HOME/bin/screen-in-dir"
   

3. Apply patch and recompile screen:
   
   • Get current Screen sources:

     
     $ git clone git://git.savannah.gnu.org/screen.git screen
     $ cd screen
     

   • Apply >> this simple patch, compile and install:

     
     $ git-apply command-tty.diff
     $ cd src; ./autogen.sh && autoheader && ./configure && make
     $ sudo make install
     

   >> file command-tty.diff - adds tty command which prints the filename of the current terminal ( bug 30563 )

4. Start Screen. Press "Ctrl-a C" to create a new window with the same working directory.

# GNU Screen how to: create a resize mode

# EscapeKey+r puts Screen into resize mode. Resize regions using hjkl keys, toggle focus with Tab and arrow keys.

bind r eval "command -c classresize" # enter resize mode

# use hjkl keys to resize regions
bind -c classresize h eval "resize -h -5" "command -c classresize"
bind -c classresize j eval "resize -v -5" "command -c classresize"
bind -c classresize k eval "resize -v +5" "command -c classresize"
bind -c classresize l eval "resize -h +5" "command -c classresize"

# quickly switch between regions using tab and arrows
bind -c classresize \t    eval "focus"       "command -c classresize" # Tab Key
bind -c classresize -k kl eval "focus left"  "command -c classresize" # Arrow Left
bind -c classresize -k kr eval "focus right" "command -c classresize" # Arrow Right
bind -c classresize -k ku eval "focus up"    "command -c classresize" # Arrow Up
bind -c classresize -k kd eval "focus down"  "command -c classresize" # Arrow Down