Using tee to create a log

[Kevin Buettner]

On Jul 26,  1:03pm, Gorman, John wrote:

> Here is an example: telnet hostname | tee hostname.log
> 
> What this does is telnet to host hostname and record the commands
> and output from that into the currenct directory as the filename
> hostname.log.
> 
> By the way, this is an excellent way to record your testing history,
> or save your actions for someone who wants to follow what you did at
> a later time.

The problem with using tee for this purpose is that stdout is no
longer connected to a tty (or even a pseudo-tty).  This means that
some programs will behave quite differently than they would have had
you not thrown the pipe in.

A better way to capture this kind of output is to use ``script''...

    ocotillo:kev$ script
    Script started, file is typescript
    ocotillo:kev$ echo foo
    foo
    ocotillo:kev$ exit
    exit
    Script done, file is typescript
    ocotillo:kev$ cat typescript 
    Script started on Thu Jul 26 13:27:14 2001
    ocotillo:kev$ echo foo
    foo
    ocotillo:kev$ exit
    exit

    Script done on Thu Jul 26 13:27:24 2001

An example of a program that behaves differently when it's connected
to a terminal vs a pipe is ``ls''.  Try doing just ``ls'' and then
``ls | cat'' (or even ``ls | tee'').  You'll find that that the former
gives you a listing with multiple columns while the latter gives you
a listing with a single column.

Kevin