Red Hat NETSCAPE MANAGEMENT SYSTEM 6.0 - CUSTOMIZATION User Manual download pdf (Page 271)

17.3 Command History and Tab Completion 259

Voila!Wenowseethecontentsofsneakers.txt.

The bash shell can store up to 1,000 commands.

Tip: By typing the env command at a shell prompt, we can see the environment

variable that controls the size of the command-line history. The line which reads, ”HIST-

SIZE=1000” tells us that bash will store 1,000 commands in its history.

The command-line history is actually kept in a ﬁle, called .bash

history in our login directory. We

canreaditinanumberofways:byusingpico, cat, less, more, and others.

Be prepared, though: the ﬁle can be pretty long.

Let’sreaditwithmore:

more .bash_history

To move forward a screen, press

Space ; to move back a screen, press B ;toquit,press Q .

Another time-saving tool is known as tab completion. If you type part of a ﬁle or pathname then hit

the

Tab key, bash will present you with either the remaining portion of a the ﬁle/path, or a beep. If

we get a beep, we can press

Tab again to obtain a list of the ﬁles/paths that match what we’ve typed

so far.

So even if we do turn off the machine at the end of the day, we probably won’t have to work too

hard in order to remember the command to update locate’s database: The chances are good that the

command will be stored in the command-line history or can be completed with tab completion (as

long as we remember the start of the pathname for the command).

Both tab completion and command-line history can be useful to help you use a command you’ve

forgotten, as well.

Let’s try tab completion to update locate’s database. First, su to root.

Now, at a shell prompt, type the beginning of the path:

/etc/cr

Now, press the

Tab key and tab completion will complete the path to /etc/cron (and you’ll hear

a beep). Press

Tab again, and you’ll be presented with a list of possible completions:

cron.daily cron.hourly cron.monthly cron.weekly crontab

1 2 ... 266 267 268 269 270 271 272 273 274 275 276 ... 299 300

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Red Hat NETSCAPE MANAGEMENT SYSTEM 6.0 - CUSTOMIZATION User Manual Page 271