Typescript - Capturing your shell activity

We know about screen capturing and recording our screen activity. There are hundreds of applications for this purpose. But what about your shell activity? Of course you can use the same screen capturing tools if you are working on the GUI window. But what if you are on a remote shell? What if you want to reuse or copy the results/commands as a backup? Obviously the graphical tools will not be of much help. This is where typescripts come into play.

A typescript is a record of whatever is printed in your terminal. That includes stdin,stdout and stderr, which is basically the commands that you type and the output that these commands generate. The command which creates the typescript is "script". You can just type the command "script" and this will start recording the shell activity to a file by the name "typescript" which will be created in the directory from which the command "script" was run. Alternatively you can specify a separate file as an argument to it. When you run the script command it actually opens a new shell, and keeps recording the shell's activity until you exit that shell and return to the parent shell from where you ran the "script"command. Let us check the usage.

safeer@penguinpower:~$ script
Script started, file is typescript
safeer@penguinpower:~$ ls MyDocuments/
Linux Windows
safeer@penguinpower:~$ mkdir MyDocuments/Cisco
safeer@penguinpower:~$ ls MyDocuments/
Cisco Linux Windows
safeer@penguinpower:~$ rm MyDocuments/Cisco
rm: cannot remove `MyDocuments/Cisco': Is a directory
safeer@penguinpower:~$ exit
exit

Script done, file is typescript

Let us examine the contents of typescript.

safeer@penguinpower:~$ cat typescript
Script started on Sunday 03 January 2010 02:05:01 AM IST
safeer@penguinpower:~$ ls MyDocuments/
Linux Windows
safeer@penguinpower:~$ mkdir MyDocuments/Cisco
safeer@penguinpower:~$ ls MyDocuments/
Cisco Linux Windows
safeer@penguinpower:~$ rm MyDocuments/Cisco
rm: cannot remove `MyDocuments/Cisco': Is a directory
safeer@penguinpower:~$ exit
exit

Script done on Sunday 03 January 2010 02:05:55 AM IST

As you can see all that is printed into the terminal is recorded in the typescript. A few useful options to use with the script:

-a : Append to the end of the type script file - if it exists already. Default behavior is to overwrite the file.
-q: Quiet mode, removes the End timestamp from the typescript.
-t: This is an interesting option, it prints the output timing data to standard error. This data can be used to replay the typescript with real-time input output delays. We will see the usage later.

You can specify an alternate typescript file as the last argument.

safeer@penguinpower:~$ script myscript
Script started, file is myscript
safeer@penguinpower:~$ echo HI
HI
safeer@penguinpower:~$ exit
exit

Script done, file is myscript

safeer@penguinpower:~$ cat myscript
Script started on Sunday 03 January 2010 02:10:28 AM IST
safeer@penguinpower:~$ echo HI
HI
safeer@penguinpower:~$ exit
exit

Script done on Sunday 03 January 2010 02:10:44 AM IST

To gather the timing information, we car try using the -t option.

safeer@penguinpower:~$ script -t myscript 2>myscript.time
Script started, file is myscript
safeer@penguinpower:~$ ls MyDocuments/
Cisco/ Linux/ Windows/
safeer@penguinpower:~$ ls MyDocuments/Cisco/
safeer@penguinpower:~$ touch MyDocuments/Cisco/gns3
safeer@penguinpower:~$ ls MyDocuments/Cisco/
gns3
safeer@penguinpower:~$ exit
exit

Script done, file is myscript

Content of time file will look like this:

safeer@penguinpower:~$ head -2 myscript.time
0.500888 27
0.253943 23

The first field indicates how much time elapsed since the previous output. The second field indicates how many characters were output this time. With this information and the typescript file we can use the command "scriptreplay" to replay our terminal activity with the same timing with which you typed on the terminal and the output was displayed. It will give you a feeling of watching a video of your terminal activity.

The usage is like this:

First get the type script to one file and the timing information obtained with "-t" option ( printed to stderr) to another file.

safeer@penguinpower:~$ script -t myscript 2>myscript.time

Now replay the typescript with the format "scriptreplay [timing file] [typescript file] ".
If no typescript filename is given, the name "typescript" is assumed.

safeer@penguinpower:~$ scriptreplay myscript.time myscript

And this will play the typescript with timing.