screen/INSTALL

Installation of GNU screen.


0.) This instruction is quite lengthy
-------------------------------------
... and there are still important items near the end. Start here:
Unpack. Screen comes as a compressed tar archive. You need gzip to 
uncompress.  And... well, you probably already managed that step, 
when you are reading this.

For general documentation on the coding and usage standards this
distributions follows, see the GNU standards document on
https://www.gnu.org/prep/standards/, especially the `Makefile
Conventions', `Configuration', and `User Interfaces' sections.

0.) autogen.sh
--------------
First, run ./autogen.sh. This will create configure file that you can use.
This should be already done, so you can skip this step.

1.) configure & config.status
-----------------------------
Run ./configure. This should create a reasonable Makefile and a config.h file
suited for your machine. Rename config.status to reflect the architecture 
(hostname) where it was built. To reconfigure quickly for that architecture
just run that config.status file.
If this process fails, try to find out what configure did do and what it
should have checked.
And then please report a bug (https://savannah.gnu.org/bugs/?group=screen
or mail screen-devel@gnu.org).
Actually the initial Makefile that comes with the distribution just runs
configure -- thus you can start by typing 'make' right after unpacking.
You will be prompted to run 'make' again, which will really make screen.

2.) Makefile & config.h
-----------------------
Look through the Makefile & user configuration section in config.h and check
pathnames. Change them to suit your installation requirements. Usually 
sysadmins discuss the location of SOCKDIR, whether it should be in /tmp or 
not. At least it must be on a filesystem that supports sockets/fifos.
SOCKDIR must not point into an AFS (Andrew File System) mounted directory. 
If you are uncertain about your NFS implementation, use a UFS directory for 
SOCKDIR. Personally, I favour a user's home directory and recommend the the
/tmp/ area. 
The path for ETCSCREENRC may also need to be adapted.

3.) how to actually compile 
---------------------------
Run 'make'. Screen should compile without too many warnings :)
The creation of term.h, comm.h, tty.c or osdef.h may fail on some machines
for some odd reason. (E.g. the sed under SCO-unix is known to be 
case-insensitive and breaks term.h.) If so, please mail a short description 
of the problem to screen-devel@gnu.org and use the files ending in .dist 
as a replacement (or in case of osdef.h retry with an empty file).
You can then try 'make install' (if you dare).

4.) where to install
--------------------
You may well run screen from your private binary directory and with a 
private socket directory like $HOME/.screen. But to have a full featured
screen and (from a user's point of view) more secure pty's you should
consult a system administrator and discuss installing screen setuid-root
in some globally accessible directory like /usr/local/bin.

Consider this, when deciding whether you install screen setuid-root:
- On some machines root privileges are required to open pty's. 
- Pty's should be owned by the user, so that she can do chmod to prevent
  intruder attacks. The PTYs used by screen will remain world read-writable
  if screen is not installed setuid-root.
- Some commands only work properly when the pty is owned by the user.
  These include mesg and biff.
- The ^At feature may need to lseek and read the kernel file to retrieve 
  the load average. 
- On most machines utmp slots can only be created/manipulated with root
  privileges. Users will appear to be logged on the primary terminal
  instead of the screen windows, if screen is not installed setuid-root.
- Multi-user screen sessions are only allowed when screen has a root-s-bit.
- If screen sockets of multiple users are kept in one directory (e.g. 
  /tmp/screens), this directory must be world writable when screen is not
  installed setuid-root. Any user can remove or abuse any socket then.
  

5.) doc/screen.1 & doc/screen.texinfo
-------------------------------------
The man page doc/screen.1 should go to /usr/local/man/man1, or some similar
directory. It should format nicely with nroff -man. If it does not, then
try removing extra dots with: sed -e 's/^\.\././' < screen.1 | nroff -man 
The info page doc/screen.texinfo contains basically the same information as
the man-page, we may have missed one or another thing in one of the files.
If so, mail me.

6.) etc/screenrc & etc/etcscreenrc
----------------------------------
The files screenrc and etc/etcscreenrc are instructive samples that
demonstrate what can/should be done from your private .screenrc and from
$ETCSCREENRC -- do not just copy them. Read them.  Look through the 
etcscreenrc file for system wide defaults that you like to set, e.g.
autodetach off, startup_message off, vbell on, ...
Since version 3.2.15 the screenrc file syntax changed slightly. All rc files
from previous versions should be run through the 'newsyntax' script that comes 
with this package.
If and only if you want to install screen as a console multiplexer, look
at the *.sample files and what 'make cscreen' suggests.

7.) terminfo/screeninfo.src & terminfo/screencap
------------------------------------------------
Every now and then we update the termcap/terminfo entries for screen. 
E.g. keycodes were added in 3.6.0 -- thus you check that your termcap/terminfo
database is up to date. See the README in the terminfo subdirectory.

8.) have fun
------------
To get an idea what the basic screen commands are, read the file README.
Request snail mail address for liquid and solid donations. :-)