the use of .screenrc file

Published on: 2024-07-19T03:07:17

Table Of Contents

The Use of .screenrc File

Overview

We can use the .screenrc file to configure environmental variables and shortcuts, manage windows, window groups and window layouts.

Usages

My daily conifguration file:

##resize max
defutf8 on
defencoding utf8
encoding UTF-8 UTF-8
setenv DISPLAY :0
    
nonblock 1
escape ^q^q
shell "/var/tmp/.scbash"

layout save 0

screen -t "root" //group
screen -t "two" //group
select 1
screen -T "screen-256color"
# screen bash --rcfile $HOME/.sptzh/.ssh-bashrc
# stuff "^j"

vbell off
# layout save def
# setenv BASH_ENV /path/to/custom_bashrc
# verbose on
attrcolor b ".I" # use bright colors for bold
defdynamictitle on
startup_message off
mousetrack off
defmousetrack off
hardstatus on
# rendition so =b wk
rendition so =b wk
# caption always "%?%F%{.B.}%? /%H /%S /%n /%t"
# caption always "%?%F%{.B.}%? /%H /%S /%n /%e"
caption always "%?%F%{kw}%? /%Y%m%d.%c:%s /%H /%S /%n /%e"
# caption always "%A||%B||%C||%D||%E||%F||%G||%H||%I||%J||%K||%L||%M||%N||%O||%P||%Q||%R||%S||%T||%U||%V||%W||%X||%Y||%Z||%a||%b||%c||%d||%e||%f||%g||%h||%i||%j||%k||%l||%m||%n||%o||%p||%q||%r||%s||%t||%u||%v||%w||%x||%y||%z"
#caption always "%s||%t||%u||%v||%w||%x||%y||%z"

# show window list in the buttom
# caption always "%{= kw}%-Lw%{= BW}%50>%n%f* %t%{= kw}%+Lw%< %{= kw}[Load:%{= Y}%D%{= kw}]%{= BW}%=%{= kw}%h/%H"
# caption always "%{= Wk}%-Lw%50>%{= BW}%n%f* %t%{= Wk}%+Lw%<"    

#hardstatus alwayslastline
#hardstatus string " %H %S %n %t "
#caption always "%{= kw}%-w%{= gW}%n %t%{-}%+w %-= bigdatums.net - %Y-%m-%d %C:%s"
altscreen on #fix residual editor text

# message display time (seconds)
msgwait 3

deflogin off

# enable logging
# deflog on
# set log location
# logfile /root/screen.%n		

# nethack off			# nethack like notifications

# backtick 0 3600 3600 printf "$USER"
# backtick 1 5 5 /bin/bash -c 'cpuLoad=$(cut -s -d\  -f13 <(uptime)); cpuLoad=${cpuLoad:0:-1}; memLoad=...; echo "CPU load ${cpuLoad} Mem Load ${memLoad}" '

multiuser on 
# addacl test1,test2

# huge scrollback buffer
defscrollback 5000

# diable welcome message
startup_message off

# scroll with mouse
termcapinfo xterm*|rxvt*|kterm*|Eterm* ti@:te@

# Change the xterm initialization string from is2=\E[!p\E[?3;4l\E[4l\E>
# (This fixes the "Aborted because of window size change" konsole symptoms found
#  in bug #134198)
# termcapinfo xterm* 'is=\E[r\E[m\E[2J\E[H\E[?7h\E[?1;4;6l'
terminfo rxvt-* 'Co#256:AB=\E[48;5;%dm:AF=\E[38;5;%dm'
# term "rxvt-256color"
# term "xterm-256color"
term "screen-256color"

# layouts
layout new two
select 2
layout save two

bind ' ' layout next # <- actually means Ctrl-q + Space
# bind ^o focus next
bind ^u focus prev
bind ^g 
bind "|" eval "split -v" "windowlist -b" "other" "focus" "other" "screen"
bind "S" eval "split" "windowlist -b" "other" "focus" "other" "screen"
bindkey "^q^o" eval "focus next" "focus next"
bindkey "^q^y" eval "focus prev" "focus prev"
# bindkey "^q^r" eval "layout save tmp" "only"
bindkey "^q^j" other
# bind "r" eval "layout save tmp" "only"
bind "r" eval "resize _" "fit" "colon" "stuff 'resize -b ='"
# bind "3" eval "layout select three"
bind "\"" select
# bind "u" eval "layout show"
bind s eval "colon" "stuff 'layout save '"
bindkey "^q^m" layout select
bind "m" layout show
# bind \' eval "windowlist -m" "stuff j"
bind \' eval "windowlist -m"
# bind g eval "screen //group" "title" "screeen"
# bind g eval "windowlist -g -m" "stuff ^?" "screen //group" "title" "stuff ^u" 
bind g eval "windowlist -g -m" "stuff ^?" "screen //group" "colon" "stuff 'eval \"title \" \"screen\" \"only\" \"layout save '" "stuff ^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b"
# bind C stuff "sudo -E bash --rcfile $(getent passwd $(ls /tmp/.scfile/) | cut -d: -f6)/.sptzh/.ssh-bashrc\n"
bind "?" eval "select root" "windowlist -g -m" "stuff /"
bind "/" eval "windowlist -g -m" "stuff j/"
# map to return
# bindkey -m "^[l" eval "stuff \015"
bindkey -m "^[j" eval "stuff jjj"
bindkey -m "^[k" eval "stuff kkk"

# bindkey -m "'" select
# bind "h" at \# stuff ". ~/.sptzh/.ssh-bashrc\n" 

# sync screen buffer to clipboard
# bindkey -m > eval "stuff ' '" writebuf "exec sh -c 'xsel -ip < /tmp/screen-exchange'"
# bindkey -m > eval "stuff ' '" writebuf "!.. /bin/bash -cx 'printf \"\\033]52;c;\$(printf \"Hello, world\" | base64)\\a\"' | less"
# bindkey -m > eval "stuff ' '" writebuf "exec /bin/bash -c 'printf \"\\033P\\033]52;c;\$(cat /tmp/screen-exchange)\\a\\033\\\\\\\\\"'"
bindkey -m > eval "stuff ' '" writebuf "exec bash -c '$(getent passwd $(cat /var/tmp/.scuser) | cut -d: -f6)/.sptzh/osc52.sh < /tmp/screen-exchange'"
# bindkey -m > eval "stuff ' '" writebuf "exec /bin/bash -cx 'echo xxx$SHELL xx $TERM'"

bind "j" eval "copy" "stuff ' H ' " writebuf "exec bash -c '$(getent passwd $(cat /var/tmp/.scuser) | cut -d: -f6)/.sptzh/osc52.sh < /tmp/screen-exchange'"

# update appearance of horizental or vertical bar
# caption string "%{11} "
# caption string "%{00}%3n %t"
# rendition so =01

# make title follow commnad executed
# windowlist string "%4n %h%=%f"

# shelltitle '$ |something'
maptimeout 100
layout attach :last
layout autosave on

Layout and Groups Management

Screen has the ability to create window groups, and nested groups, helping to organise windows efficiently.

screen -t "root" //group
screen -t "two" //group
select 1
screen -T "screen-256color"

Screen doesn't have command to switch window groups directly, but it can be done indirectly using layout. If you create a layout named "two" and configure it with screen -t "two" //group, you can switch to group "two" using the layout command layout select two.

layout new two
select 2
layout save two

You can create a new layout, select and display layouts.

bind s eval "colon" "stuff 'layout save '"
bindkey "^q^m" layout select
bind "m" layout show

To create a new window group, type the group name in palce of the two "_" cursor positions and add a " in the end of the command: :eval "title _" "screen" "only" "layout save _".

bind g eval "windowlist -g -m" "stuff ^?" "screen //group" "colon" "stuff 'eval \"title \" \"screen\" \"only\" \"layout save '" "stuff ^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b^b"

Save the layout when detaching Screen to recover the previous layout when reattaching.

layout attach :last
layout autosave on

Window Management

Set the following option to name windows dynamically, making it easier to search for them easily in the window list.

defdynamictitle on

Using only one region in a Screen window wastes space. Typically I create at least 3 regions, sometimes even 6. To switch between them fluently, I use <C-q><C-u> and <C-q><C-i> to select previous and next region. I also create shortcuts to move two region at a time which is efficient when working with 6 regions.

bind ^u focus prev
bindkey "^q^o" eval "focus next" "focus next"
bindkey "^q^y" eval "focus prev" "focus prev"

Using two different characters to trigger a command is quicker.

bindkey "^q^j" other

Regions are initially split with blank content, but we usually create a window in it. Use shortcuts to replace the default ones.

bind "|" eval "split -v" "windowlist -b" "other" "focus" "other" "screen"
bind "S" eval "split" "windowlist -b" "other" "focus" "other" "screen"

Sometimes a region is too small, to temporarily maximise it, use the shortcut below, then <C-M> to restore.

bind "r" eval "resize _" "fit" "colon" "stuff 'resize -b ='"

You can display window list of current window group in the order of most recently used.

bind "\"" select
bind \' eval "windowlist -m"

You can search windows by name. The first line searches within the current group, while the second searches across all groups.

bind "/" eval "windowlist -g -m" "stuff j/"
bind "?" eval "select root" "windowlist -g -m" "stuff /"

You can use <M-j> and <M-k> to move quickly through the window group list.

bindkey -m "^[j" eval "stuff jjj"
bindkey -m "^[k" eval "stuff kkk"

Navigation Bar

Hardstatus is useful for displaying the window infomation or indicating the currently active window.

hardstatus on
# rendition so =b wk
rendition so =b wk
# caption always "%?%F%{.B.}%? /%H /%S /%n /%t"
# caption always "%?%F%{.B.}%? /%H /%S /%n /%e"
caption always "%?%F%{kw}%? /%Y%m%d.%c:%s /%H /%S /%n /%e"

After exiting Emacs or Vim, Residual content may remain on the screen, enable the option to clear them.

altscreen on #fix residual editor text

System Clipboard

You can copy highlighted content to clipboard, even it's in a remote SSH connection.

bindkey -m > eval "stuff ' '" writebuf "exec bash -c '$(getent passwd $(cat /var/tmp/.scuser) | cut -d: -f6)/.sptzh/osc52.sh < /tmp/screen-exchange'"

osc52.sh:

#!/bin/sh
# Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

# Max length of the OSC 52 sequence.  Sequences longer than this will not be
# sent to the terminal.
OSC_52_MAX_SEQUENCE="100000"

# Write an error message and exit.
# Usage: <message>
die() {
  echo "ERROR: $*"
  exit 1
}

# Send a DCS sequence through tmux.
# Usage: <sequence>
tmux_dcs() {
  printf '\033Ptmux;\033%s\033\\' "$1"
}

# Send a DCS sequence through screen.
# Usage: <sequence>
screen_dcs() {
  # Screen limits the length of string sequences, so we have to break it up.
  # Going by the screen history:
  #   (v4.2.1) Apr 2014 - today: 768 bytes
  #   Aug 2008 - Apr 2014 (v4.2.0): 512 bytes
  #   ??? - Aug 2008 (v4.0.3): 256 bytes
  # Since v4.2.0 is only ~4 years old, we'll use the 256 limit.
  # We can probably switch to the 768 limit in 2022.
  local limit=256

  if [ "$2" -eq "1" ]; then
    # We go 4 bytes under the limit because we're going to insert 2 bytes
    # before (\eP) and 2 bytes after (\e\) each string.
    echo -n "$1" | \
      sed -E "s:.{$(( limit - 4 ))}:&\n:g" | \
      sed -E -e 's:^:\x1bP:' -e 's:$:\x1b\\:' | \
      tr -d '\n'
  elif [ "$2" -eq "2" ]; then
    # We go 10 bytes under the limit because we're going to insert 4 bytes
    # before (\eP\eP) and 6 bytes after (\e\) each string.
    echo -n "$1" | \
      sed -E "s:.{$(( limit - 10 ))}:&\n:g" | \
      sed -E -e 's:^:\x1bP\x1bP:' -e 's:$:\x1b\x1b\\\x1b\\\\:' | \
      tr -d '\n'
  fi
}

# Send an escape sequence to hterm.
# Usage: <sequence>
print_seq() {
  local seq="$1"

  case ${TERM-} in
  screen*)
    # Since tmux defaults to setting TERM=screen (ugh), we need to detect
    # it here specially.
    if [ -n "${TMUX-}" ]; then
      tmux_dcs "${seq}"
    else
      screen_dcs "${seq}" "${SCREEN_LEVEL:-1}"
    fi
    ;;
  tmux*)
    tmux_dcs "${seq}"
    ;;
  *)
    echo -n "${seq}"
    ;;
  esac
}

# Base64 encode stdin.
b64enc() {
  base64 | tr -d '\n'
}

# Send the OSC 52 sequence to copy the content.
# Usage: [string]
copy() {
  local str

  if [ $# -eq 0 ]; then
    str="$(b64enc)"
  else
    str="$(echo "$@" | b64enc)"
  fi

  if [ ${OSC_52_MAX_SEQUENCE} -gt 0 ]; then
    local len=${#str}
    if [ ${len} -gt ${OSC_52_MAX_SEQUENCE} ]; then
      die "selection too long to send to terminal:" \
        "${OSC_52_MAX_SEQUENCE} limit, ${len} attempted"
    fi
  fi

  print_seq "$(printf '\033]52;c;%s\a' "${str}")"
}

# Write tool usage and exit.
# Usage: [error message]
usage() {
  if [ $# -gt 0 ]; then
    exec 1>&2
  fi
  cat <<EOF
Usage: osc52 [options] [string]

Send an arbitrary string to the terminal clipboard using the OSC 52 escape
sequence as specified in xterm:
  https://invisible-island.net/xterm/ctlseqs/ctlseqs.html
  Section "Operating System Controls", Ps => 52.

The data can either be read from stdin:
  $ echo "hello world" | osc52.sh

Or specified on the command line:
  $ osc52.sh "hello world"

Options:
  -h, --help    This screen.
  -f, --force   Ignore max byte limit (${OSC_52_MAX_SEQUENCE})
EOF

  if [ $# -gt 0 ]; then
    echo
    die "$@"
  else
    exit 0
  fi
}

main() {
  set -e

  while [ $# -gt 0 ]; do
    case $1 in
    -h|--help)
      usage
      ;;
    -f|--force)
      OSC_52_MAX_SEQUENCE=0
      ;;
    -*)
      usage "Unknown option: $1"
      ;;
    *)
      break
      ;;
    esac
    shift
  done

  copy "$@"
}
main "$@"

You can copy content from cursor position to the top of a terminal quickly to clipboard using the following shortcuts.

bind "j" eval "copy" "stuff ' H ' " writebuf "exec bash -c '$(getent passwd $(cat /var/tmp/.scuser) | cut -d: -f6)/.sptzh/osc52.sh < /tmp/screen-exchange'"

Miscellaneous

Change the escape key because the default ^a is often used in Bash, while ^q is used for quote insertion in Bash and Emacs and is rarely needed, so it's a good choice to use ^q.

escape ^q^q

If you run Screen on a remote server and the TCP connection becomes unstable, Screen may get blocked. To recover from a blocked state after 1 second, set the following option:

nonblock 1

Set long scrollback buffer to retain more history information.

defscrollback 5000

Enable mouse support in GNU Screen.

termcapinfo xterm*|rxvt*|kterm*|Eterm* ti@:te@

Specify the terminal type to enbale the 256-color support.

terminfo rxvt-* 'Co#256:AB=\E[48;5;%dm:AF=\E[38;5;%dm'
term "screen-256color"

Turn off the welcome page.

startup_message off

Mouse track is useful when switching between many regions, but it doesn't work well on 2K monitors, so I disable it. I found that clicking the right-most window activates the left most one, which is incorrect.

mousetrack off
defmousetrack off

Showing message for long time is annoying, so I reduce it to 3 seconds.

# message display time (seconds)
msgwait 3

Diable login to prevent entries from appearing in the w command output. This can avoid causing concern for customers if there are many login terminals.

deflogin off

I unbind ^g to avoid accidentally switching to vbell mode when using Emacs.

bind ^g 

Shorten the delay between inputs when using escape sequence.

maptimeout 100

Other Resources

I get osc52.sh from https://chromium.googlesource.com/apps/libapps/+/master/nassh/doc/FAQ.md#Is-OSC-52-aka-clipboard-operations_supported.