Unix Commands - Beginning

Question 1

kernel

Answer 1

manages processes, devices, and memory.

Question 2

shell

Answer 2

interface between kernel and user. interpreter of commands.

Question 3

file system

Answer 3

hierarchy of directories, subdirectories and files.

Question 4

standard input

Answer 4

what user types.

Question 5

standard output

Answer 5

resulting text from the process of a command.

Question 6

passwd

Answer 6

command for password. password is not visible in shell. login is lowercase. commands are case sensitive.

Question 7

logout

Answer 7

ends session

Question 8

pwd

Answer 8

print working directory. shows pathway of current directory.

Question 9

cd

Answer 9

change directory. can accept argument.

Question 10

flags

Answer 10

single letter abbreviations that modify commands.

Question 11

arguments

Answer 11

typically file names input after a command.

Question 12

ls

Answer 12

lists directories and all files. -a lists all entries.

Question 13

-l (lowercase L)

Answer 13

prints list in long format. gives mode, links. owner, size and time of last mod.

Question 14

-F

Answer 14

visualization of contents being linked. these are / after names of directories. * is executable file. @ is link.

Question 15

-1 (number one)

Answer 15

prints each file name on separate line.

Question 16

-d

Answer 16

lists directory names without contents

Question 17

-h

Answer 17

human readable. prints sizes in easy formats. flags do not require arguments and can be input together.

Question 18

mkdir

Answer 18

make directory. argument is required. needs to know name of directory to create.

Question 19

-p

Answer 19

parent. creates all files in directory that do not yet exist.

Question 20

-cat

Answer 20

concatenate - writes the specified file as argument to standard output.

Question 21

more [file]

Answer 21

writes the specified file as an argument to std output one screen at a time.

Question 22

head [count] [file]

Answer 22

prints a certain number of lines from the specified output file. if not specified then standard number is ten.

Question 23

tail [-f] [-c number] [-n number]

Answer 23

prints the lines of a specified file beginning at a certain place. if no flags are indicated, then default is ten lines.

Question 24

sort

Answer 24

sorts files based on sorting criteria. ordered in ascending order as default. -r for reverse sorting. -n sorts lines numerically.

Question 25

move file1 [file2] target

Answer 25

moves the file to the location specified at target.

Question 26

copy file1 [file2]

Answer 26

copies the files to one target.

Question 27

grep [c] [-n] [file]

Answer 27

searches titles for a pattern. and prints lines containing the pattern.

• c is number of lines containing pattern.
• n prints out line number where the file is found.

Question 28

alias [alias_namestring}

Answer 28

defines aliases which are set when a command is used often or is very long. alias_name sets new name for the command. the original name must be entered in quotation marks.

Question 29

unalias

Answer 29

alias-name removes alias definition. -a will remove all aliases assigned in the session.

Question 30

echo [n] [arg]

Answer 30

writes arguments separated by blanks and terminated by a new line. a single echo command prints the line to standard output.

Question 31

wc

Answer 31

word count.

[-c | m] [-lw] will count the number of words, lines, characters in a file. -1 counts lines in a file.

Question 32

ln [-sif] file1 [file2] target

Answer 32

links files together. if user wants to access a file in another directory that may be too large to copy, the files may be linked.

Question 33

rm

Answer 33

removes files. YOU CANNOT RETRIEVE FILES ONCE REMOVED.

Question 34

man

Answer 34

prints out description of a commands, its uses, and syntax.

Question 35

apropos [keyword]

Answer 35

prints out list of commands containing the keyword in their description. this is used when you don’t know what command to use for a particular job.