Searching and Extracting Data From Files

Question 1

Command Line Pipe / Pipeline

Answer 1

The output of first command is used and input for the second command

Question 2

Xargs command

Answer 2

Enables a user to generate command line options from files or other programs’ output

Question 3

Standard Output

Answer 3

Normal program messages

Question 4

Standard Error

Answer 4

Any error messages

Question 5

/dev/null

Answer 5

Device file that serves as a trash bin for output/errors

Question 6

cat command

Answer 6

display contents of a file.

Question 7

wc command

Answer 7

Word count of file
-l line count

Question 8

head -# command

Answer 8

Return first # things from a file

Question 9

tail -# command

Answer 9

Return last # things from a file

Question 10

Regular Expressions

Answer 10

• A way to describe patterns that a user might want to look for in data files
• Similar to wild cards

Question 11

File-Archiving Tool

Answer 11

Collects a group of files into a single “package” file to easily move around on a single system

Question 12

tar file.tar /dir command

Answer 12

(Tape archiver)
Used to archive various data files into a single files (archive file) while the original files remain on the disk

Question 13

tarball

Answer 13

Archive file created from tar command

Question 14

grep command

Answer 14

Search inside a file
Search for file that contain a specified string

Question 15

/dev

Answer 15

A virtual or pseudo filesystem used to interface with the kernel and system as a whole but not with individual processes

Question 16

tar -c command

Answer 16

Create a new .tar archive file

Question 17

tail/head -c

Answer 17

Print last/firs x bytes of data to the screen

Question 18

cat -n

Answer 18

Display line numbers with the text of a file to the screen

Question 19

tail -f command

Answer 19

Print the last 10 lines of a file (usually a log file) and continue to print out new lines to the screen as they are added to the file