For the Record

Recording your desktop can serve many purposes: It can be a way of permanently recording a complicated procedure; it can prove that a student has completed an assignment, as the man page for the script command suggests; or it can enhance documentation, provide animated how-tos, and even assist with automatic testing, depending on the tools you choose.

The tools described in this article operate on several levels. At the simplest level, commands like script, ttyrec, and shelr serve as more permanent alternatives to a shell's history. By contrast, scrot takes stills, cnee records not so much visual events as the technical information behind them, and recordmydesktop produces movies made from desktop events. You could accurately say that recording tools are available for every purpose and level of users.

script

The script command writes a record of all actions within a shell (Figure 1). It is not much different from viewing a shell's history, except that it writes to file and is stored permanently. Script is one of several dozen commands installed in distributions as part of the linux-utils package.

Figure 1: The script command records shell sessions.

Once started, script records every command entered and its output. You can add annotations at the command line between commands if desired. These annotations can be located later by searching for the "command not found" that the shell adds after them.

At its simplest, script runs from the bare command, saving to the file typescript and ending when you press Ctrl+D. However, you can record to whatever file you want with the command script FILE.

You can further specify how the recording file is used with the option -a or --append to add new input at the bottom of the content of a previous session. You can use -f or --flush to remove previous content and write to the same file.

Additionally, you can start script with the name of the command you want to run. For example, you can start script and vi together with the command:

script --command vi FILE

After recording, you can read the output file with less, more, or cat.

ttyrec, ttytime, and ttyplay

The three related commands ttyrec, ttytime, and ttyplay are intended as an improved version of script – to be exact, a simplification and a division into three separate commands. Unless another file is specified, the ttyrec command saves to ./ttyrecord. You can use the -a option to append the current recording to a previously record file or use -e COMMAND to start the command within another application.

Unlike script, ttyrec contains no GNU options (longer commands prefixed with two hyphens). It does include an option for uuencode for protection when transferring remote files, but because uuencode is practically obsolete today, you should check first that the file's receiver knows how to read them.

Once a recording is finished, you can use ttytime FILE to see a file's length in seconds. This function may help you to identify the contents of the file when the name does not.

To play a recording, use the command ttyplay FILE. Options in ttyplay are mostly for speed. The -s SPEED option is a multiple of the default speed. During playback, you can double the speed by pressing either + or f and halve it by pressing - or s. Similarly, pressing 1 returns the playback to normal speed, and pressing 0 stops playback until 1 is pressed again.

Shelr

Shelr is a combination of script and ttyrec that records terminal output and replays it in the terminal (Figure 2). Like many Debian commands, it consists of the basic command, followed by sub-commands. More unusually, it includes no options to modify behavior, but this simple structure is still adequate for its purpose.

Figure 2: Shelr records events in the terminal and replays them.

To begin recording terminal events, enter the command shelr record. After you give the recording a name, Shelr will continue to record until you either type exit or press Ctrl+D, then it will save the recording to a file in the sub-directory ~/.local/share/shelr.

The saved file has a random number for a name, but users are apparently not expected to interact directly with the file. Instead, you can use shelr list to see a list of recordings, each with the name you entered to start recording.

To replay, run shelr play RECORDING. Alternatively, you can enter the full path, or on the local machine, run replay last to show the last recording you made. The playback in all these cases takes a moment to start and can slow when replaying typing, then speed up when a program produces standard input.