CS 3377 Dollinger UNIX Exam 1

What's an absolute path name?

An absolute path name is relative to the root directory and can be used/referenced from any working directory. Absolute path names start with a slash.

ex)

{cslinux1:~} ls /home/013/v/vp/vpn200000/two

What's a relative path name?

A relative path name is relative to the working directory and can only be used/referenced from that working directory.

ex)

{cslinux1:~} cd two

What are three different ways to return to the home directory?

cd

cd ~

cd $home

What is the arrangement of directories and files in the UNIX file system?

The heirarchy starts with the /root, which branches off into /usr and /home directories. The /usr directory then branches off into the /local and /bin directories. Within the home directory are any files you create.

(i think this is all u need to kno)

What is the directory you're in when you first login? (what's the default directory?)

/home/{username}

ex)

/home/013/v/vp/vpn200000

What does .. do?

.. represents the parent directory. If you use it with cd, you can go back one directory.

ex)

{cslinux1:~} cd temp

{cslinux1:~/temp} cd ..

{cslinux1:~}

You can also use this with another directory at the same time to jump back and go into a different directory

ex)

{cslinux1:~} cd temp

{cslinux1:~/temp} cd ../temp2

{cslinux1:~/temp2}

What does . do?

. represents the current directory. However, we usually use it with a slash to execute a file.

ex)

{cslinux1:~} ./test

What is the command that gives you helpful information about a utility?

man [utility]

ex)

{cslinux1:~} man echo

What symbol do hidden files in a directory start with?

.

(a dot)

ex)

/home/user/. config

If you set a variable value in the shell, how do you display it?

echo $myvariable

ex)

{cslinux1:~} myname=arthur

{cslinux1:~} echo $myname

arthur

What does echo $PATH do?

$PATH is an environment variable that has a list of all the directories the system checks before running commands or executable files. echo $PATH will tell you what's stored in this env variable.

What's the command and the option to see everything about a file?

ls -l [filename]

The command is ls, and the option is -l.

ex)

{cslinux1:~} ls -l all

-rwx------ 1 vpn200000 sn 63 Feb 10 04:42 all

What's the symbol you use for the PID inside a shell script?

ex)

(inside a shell script)

#!/bin/bash

echo "The PID of this process is "

What's the command for changing permissions of a file?

chmod [options] [permissions] [file name]

permission users:

- owner (u)

- group (g)

- others (o)

permission types:

- read (r)

- write (w)

- execute (x)

1) if you don't include a user, the permissions will be applied to everyone

2) put a + in front of these types to add permissions

3) put a - in front of these types to remove permissions

ex)

{cslinux1:~} chmod u+x temp

{cslinux1:~} chmod +rwx temp

What's the command that copies files?

cp [originalfilename] [copiedfilename]

ex)

{cslinux1:~} cp hello copiedHello

What's the command that tells you the information about a file?

ls -l [filename]

What's the command you use on a file to display one page of information at a time?

more [options] [filename]

What's the command to make links?

ln [option] [absolutepath] [linkname]

What's the command that outputs the contents of a text file?

cat [filename]

ex)

{cslinux1:~} cat days

Monday

Tuesday

Wednesday

Thursday

Friday

Saturday

Sunday

{cslinux1:~}

What's the command that searches for patterns within a text file?

grep [options] [pattern] [files]

ex)

{cslinux1:~} grep "T" days

Tuesday

Thursday

{cslinux1:~}

What's the command that makes a new subdirectory?

mkdir [directoryname]

ex)

mkdir newDirectory

What's the command that displays information about the users that are currently logged onto the system?

who

What's the command that deletes a nonempty directory?

rm -r [directoryname]

OR

rmdir -r [directoryname]

If I touch a file name, and the file name doesn't already exist, will the touch command create it?

Yes

Within a shell script, what are the symbols that contain the arguments to the command line?

$0 = name of calling program

$1 = first command line argument

$n = nth command line argument

$* = all positional parameters

$# = total number of positional parameters

If you set a variable on the shell and you want a script to be able to read and display it, what command do you have to use on the variable to be available and understood in scripts?

export variableName=value

How do you read in a value from the shell?

read [variablename]

ex) (inside the script)

#!/bin/bash

echo "Enter the user name: "

read first_name

What does the find command do?

find [options] [pattern]

find command searches for files

ex)

find . -name *.txt

# finds all text files in the current directory

What does find -name do?

-name is an option for the find command; it searches for files based on its name

What's the command to list all your files that only start with a dot?

ls .*

What's a shell metacharacter that matches more than one character?

* (asterisk)

ex)

ls *.txt

What's a shell metacharacter that matches only one character?

? (question mark)

ex)

ls ?

# this lists all files that have only one character in their name

What's the character for a pipe?

| (absolute value thing)

pipes redirect ouput to somewhere else, for example, to a file

ex)

{cslinux1:~} cat days | grep T | sort

Thursday

Tuesday

{cslinux1:~}

# redirects output of this command to the file sort

When in vim, what keystroke do you enter to be able to use command mode?

ESC

:wq!

When in vim, what keystroke do you enter to be able to use the editor?

i

When you first pull up vim, what mode is it in?

command mode

When in vim, what's the command to list the contents of the file and to exit the editor?

to list the contents, file [filename]

to exit, ESC :wq!

What do all commands in vim start with?

:

(a colon)

Identify parts of the output of the ls-l command.

[permissions] [link count] [user] [group] [file size] [date] [time] [file name]

ex)

{cslinux1:~} ls -l

total 1592

-rw------- 1 vpn200000 sn 10 Feb 10 19:43 temp

-rw------- 1 vpn200000 sn 4 Feb 10 19:47 temp2

Can you use chmod on files you don't own?

You can only do it if you have write permissions. Otherwise, no.

Can you do ls -l and see permissions on all files or just your own?

You can see all files in the directory, no matter if you own them or not

What's a root?

Roots let you go anywhere and give you absolute authority to do anything you want.

** not sure ab this one but that's wat he said

If I touch a file that already exists, does it go back to having default permissions?

No, it keeps its previous permissions.

Define a token

A token is a sequence of one or more nonblank characters

What symbol do options start with?

-

(hyphen)

Be able to identify a command that has zero options.

ex)

ls

echo

What's a common command that is a builtin?

echo

Understand how to do piping

piping redirects output

use |

What's the comment you need on the first line of a script if you want to make sure it gets executed?

#!/bin/bash

(called shebang line)

What are the two metasymbols to put in front a script to make it run correctly?

./

Do you have to put symbols in front of a function in order to properly execute it?

no

What's the correct syntax for an alias?

alias [aliasname]='[originalname]'

ex)

{cslinux1:~} alias d='date'

{cslinux1:~} alias d

alias d='date'

{cslinux1:~}

Given a file with days of the week, execute grep and identify the output.

ex)

{cslinux1:~} grep "T" days

Tuesday

Thursday

{cslinux1:~}

Where do you store functions or variables that you want to be available when you log on?

Store them in shell configuration files like ~/.bashrc