Red Hat NETSCAPE MANAGEMENT SYSTEM 6.0 - CUSTOMIZATION Instrukcja Użytkownika Pobierz pdf (Strona 276)

264 Managing Files and Directories

I/O Redirection and Pipes

And don’t forget about using pipes and output redirection when you want to store and/or print

information to read at a later time.

You can, for example, use grep to search for particular contents of a ﬁle, then have those results

either saved as a ﬁle or sent to a printer.

To print the information about references to “coffee” in sneakers.txt, for example, we just type:

grep coffee sneakers.txt | lpr

This command behaves similar to the command ls -al /etc | more, which you may have used

in Chapter 16 on page 217 to list the contents of the /etc directory then send the results through the

more command for viewing on the screen.

Tip: Remember the distinction of using > and >>:using> will overwrite a ﬁle, while

>> appends the information to a ﬁle. Usually, unless you’re certain you want to, it’s

safer to use >>,becauseyouwon’t lose potentially valuable information (though you

may have to edit the ﬁle if you didn’t want to append information to it).

Wildcards and Regular Expressions

What if you forget the name of the ﬁle you’re looking for? You can’t say to your computer, “Find a

ﬁle called ’sneak’ or ’sneak-something’.”

Well, yes you can, in a way. Using wildcards or regular expressions, you can perform actions on a ﬁle

or ﬁles without knowing the complete ﬁlename. Just ﬁll out what you know, then substitute the

remainder with a wildcard.

Tip: To read more about wildcards and regular expressions, take a look at the bash

man page (man bash). Remember that you can save the ﬁle to a text ﬁle by typing man

bash | col -b > bash.txt. Then, you can open and read the ﬁle with less or

pico (pico bash.txt). If you want to print the ﬁle, be prepared: It’squitelong.

We know the ﬁle’s called “sneak-something.txt”,sojusttype:

ls sneak*.txt

and there’s the name of the ﬁle:

1 2 ... 271 272 273 274 275 276 277 278 279 280 281 ... 299 300

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