CS 3377 Exam 1 Review(236***)
With ls command, use this option to list all the "dot" files (configuration files that begin with a period, such as .login or .profile).
-a
This "find" command option will go and look at all the files first before hitting any of the directories or sub-directories.
-depth
What is the official name of the passwd file ?
/etc/passwd
What represents an absolute path?
/usr/bin/cat
Only Others can execute the file
0001
Only Others can write the file
0002
Only Others can read the file
0004
Only Group can execute the file
0010
Only Group can write the file
0020
Only Group can read the file
0040
Only Owner can execute the file
0100
Only Owner can write to the file
0200
Only Owner can read the file
0400
With this option of chmod command, Owner can read, and write the file; group can read the file, and other cannot access the file.
0640
With this option of chmod command, Owner can read, and write the file; group and other can read the file.
0644
With this option of chmod command, Owner can read, write, and execute the file; group and other can execute the file.
0711
With this option of chmod command, Owner can read, write, and execute the file; group and other can read and execute the file.
0755
With this option of chmod command, Owner, group, and others can read, write, and execute the file.
0777
PID of init process is
1
What would be the result (the number of the output lines) of the following grep command with the data.txt as shown below. grep '^[0-9][0-5][0-6]' data.txt where the content of data.txt is: 48 Dec 3BC1997 CPPX 68.00 LVX2A 138 483 Sept 5AP1996 USP 65.00 LVX2C 189 47 Oct 3ZL1998 CPPX 43.00 KVM9D 512 219 dec 2CC1999 CAD 23.00 PLV2C 68 484 nov 7PL1996 CAD 49.00 PLV2C 234 483 may 5PA1998 USP 37.00 KVM9D 644 216 sept 3ZL1998 USP 86.00 KVM9E 234
1
Sticky bit
1000
Consider the following program code. How many times will it output "Hello"? main() { fork( ); fork( ); fork( ); fork( ); printf("Hello"); }
16
What would be the result (the number of the output lines) of the following grep command with the data.txt as shown below. grep '[Ss]ept' data.txt where the content of data.txt is: 48 Dec 3BC1997 CPPX 68.00 LVX2A 138 483 Sept 5AP1996 USP 65.00 LVX2C 189 47 Oct 3ZL1998 CPPX 43.00 KVM9D 512 219 dec 2CC1999 CAD 23.00 PLV2C 68 484 nov 7PL1996 CAD 49.00 PLV2C 234 483 may 5PA1998 USP 37.00 KVM9D 644 216 sept 3ZL1998 USP 86.00 KVM9E 234
2
What would be the result (the number of the output lines) of the following grep command with the data.txt as shown below. grep '^[^48]' data.txt where the content of data.txt is: 48 Dec 3BC1997 CPPX 68.00 LVX2A 138 483 Sept 5AP1996 USP 65.00 LVX2C 189 47 Oct 3ZL1998 CPPX 43.00 KVM9D 512 219 dec 2CC1999 CAD 23.00 PLV2C 68 484 nov 7PL1996 CAD 49.00 PLV2C 234 483 may 5PA1998 USP 37.00 KVM9D 644 216 sept 3ZL1998 USP 86.00 KVM9E 234
2
Sets the group ID when the program is executed
2000
What would be the result (the number of the output lines) of the following grep command with the data.txt as shown below. grep '48[34]' data.txt where the content of data.txt is: 48 Dec 3BC1997 CPPX 68.00 LVX2A 138 483 Sept 5AP1996 USP 65.00 LVX2C 189 47 Oct 3ZL1998 CPPX 43.00 KVM9D 512 219 dec 2CC1999 CAD 23.00 PLV2C 68 484 nov 7PL1996 CAD 49.00 PLV2C 234 483 may 5PA1998 USP 37.00 KVM9D 644 216 sept 3ZL1998 USP 86.00 KVM9E 234
3
[Unix&Shell4grep] What would be the result (the number of the output lines) of the following grep command with the data.txt as shown below. grep '[0-9][0-5][0-6]' data.txt where the content of data.txt is: 48 Dec 3BC1997 CPPX 68.00 LVX2A 138 483 Sept 5AP1996 USP 65.00 LVX2C 189 47 Oct 3ZL1998 CPPX 43.00 KVM9D 512 219 dec 2CC1999 CAD 23.00 PLV2C 68 484 nov 7PL1996 CAD 49.00 PLV2C 234 483 may 5PA1998 USP 37.00 KVM9D 644 216 sept 3ZL1998 USP 86.00 KVM9E 234
4
Sets the user ID when the program is executed
4000
How many times printf() is executed in the following program code? main() { for (int i=0;i<3;i++) fork(); printf("pid= %d\n",getpid()); }
8
This points out the one which is not a section of "man" page
BRIEF
What is not an advantage or a feature of CVS?
CVS can manage well a complex distributed source control
What will the following command do? chmod og+r *.jpg
Change the permissions on any file ending with .jpg to be readable by all others
Which expression shows the proper way to add the directory /usr/bin to your path?
PATH=$PATH:/usr/bin
Which of the following signals cannot be handled or ignored?
SIGKILL
Default action of SIGSEGV is
Start Core dump
Which of the following values for STAT (status) column of ps command is NOT correct?
Status E means exited
Make the file executable only if it is a directory
X
A Graphical User Interface supported by every Unix system is generally known as
X Windows
A new line (in echo) will be done with this
\n
When you use the ln command, which of the following occurs?
a file is created that points to an existing file
What is a shell in UNIX?
a program through which users can issue commands to UNIX
*
a single character followed by an *
Mark one (of the choices below) which is not a help facility. man about info --help
about
Which command option (of ar command) is used to add a file to the library?
ar -r
Which of the following is not a UNIX file type? plain file special file batch file directory file
batch file
This will print a calendar for a specified month and/or year.
cal
Which command will print the contents of all files in the current directory whose names start with the character "a" and end with a period (".") followed by any two characters followed by a number?
cat a*.??[0-9]
To create a new file "new.txt" that is a concatenation of "file1.txt" and "file2.txt" is done by which command?
cat file1.txt file2.txt > new.txt
Change the current directory to /usr/local/bin
cd /usr/local/bin
chmod
change file security setting
cd
change to another directory
[]
characters inside will be matched
This changes the permission information associated with a file
chmod
The file "mypage.html" has permissions set for read and write only for owner. Which of the following command will change the permissions so that the file can be viewed on the WWW?
chmod og+r mypage.html
This displays the differences between two files on a byte-by-byte basis
cmp
Which command is used to check out the files in RCS?
co -l
The delimiter (to separates one piece of path name from other path name) in PATH variable is a
colon
This compares sorted files
comm
What is the generic syntax for all UNIX commands?
command name, followed by options, followed by arguments
Which command is used to update the files in CVS?
commit
This configures the source code automatically
configure
cp
copy a file
Make a copy of file "upper" in the directory two levels up.
cp upper ../..
This creates an archive, restores files from an archive, or copies a directory hierarchy
cpio
Keeps a set of programs current (to compile, link edit, clean, etc).
current
This selects characters or fields from input lines and writes them to standard output
cut
Which is NOT a version control tool used in UNIX?
cygwin
This displays the current day, date, time, and year
date
To show only the current month-name is:
date +%h
In Unix, if you wanted to allow a user to delete a file, you would give the file the what permission?
delete
rmdir
delete a directory
This reports file system disk usage (i.e., the amount of space taken up on mounted file systems).
df
Which command is used to display lines of source code in gdb debugger?
display
pwd
display current working directory
This reports disk usage (i.e., the amount of space taken up by a group of files).
du
The directory "a" contains its subdirectory "b" and there is no other entry in the directory "a". You want to display "the contents of directory a are: b". The contents are to be displayed using "ls" command. Which command helps you accomplish that?
echo "The contents of directory a are: `ls a`"
There is a variable "var". Its value is set to the number 5. If one tries to print "The value: 5". Which one of the commands will do that?
echo "The value: $var"
The file "assign4.html" has permissions set as: "r w x r w x r w x". This means what ?
everyone can read, write, and execute the file
This (utility) evaluates an expression and sends the result to standard output
expr
(T/F) Consider a file abc which can be "read, write, execute" only by the owner. After the command "chmod o+x abc", the file "abc" is executable by group.
false
(T/F) The command "grep -i hello" prints all the lines in file, not containing the string "hello".
false
(T/F) The command pwd is normally used to change the password.
false
The command history prints ALL the commands you typed.
false
This displays the classification of a file
file
This is most commonly used to find all of the files that have a certain name.
find
_____ is a very powerful tool and command, searching through the system or just current directory, locating all or certain files or directories.
find
This command is to find all '*.txt' files in the current directory you are in and any sub-directories,
find . -name "*.txt" -print
This is ___ to find files with a permission of ____ which is "read, write and executable" by owner and "read and execute" by everyone else.
find . -perm 755 -print
To find files that are over 10 blocks in length (that's 512 bytes a block) use:
find . -size +10 -print
To find files that are over 10 bytes in length using the character format use:
find . -size +10c -print
To find files in /var/adm directory that have not been modified in the last five days:
find / -mtime +5 -print
To find all files that have been modified in the last five days:
find / -mtime -5 -print
This find command does find all the ordinary files and then test each file for its type
find / -type f -print | xargs file
This is to find all the files in the /apps directory but do not search in /apps/bin:
find /apps -name "/apps/bin" -prune -o -print
To find all files but not directories in /etc
find /etc !-type d -print
This find command does find first for all 'passwd*' files, for example passwd, passswd.old, passwd.bak, then runs grep to see if there is a user 'richard' located in the files.
find /etc -name "passwd*" -exec grep "richard" {} \;
To find all directories in /etc
find /etc -type d -print
To find all symbolic linked files in /etc:
find /etc -type l -print
This find command does find all ordinary files older then 7 days in /var/logs and delete them.
find /var/logs -type f -mtime +7 -exec rm {} \;
This utility displays the usernames of users, together with their full names, terminal device numbers, times they logged in, and other information
finger
Creates a process by spawning a process
fork
Which of these is not a common UNIX shell discussed in class (or textbook or lecture)? bash sh fresh ksh
fresh
This utility verifies the integrity of a filesystem and reports on and optionally repairs problems it finds.
fsck
Sets the specified permissions to those of the group
g
This ___ will compile C and C++ programs
gcc
This searches for a pattern in files
grep
What is the command to search all files in your current directory for the word "hello"?
grep hello *
This displays the beginning of a file
head
How do you print the first 15 lines of all files ending by ".txt"?
head -15 *.txt
man
help manual
A user issues the following command sequence: $ a.out & $ bash $ a.out & If the user kills the bash process, then
init process becomes parent of second a.out process
If a program executing in background attempts to read from the default STDIN (that is, keyboard), then
its execution will be suspended
This reports any programs that you suspended and still have running or waiting in the background
jobs
This joins lines from two files based on a common field
join
Use this as a last resort to destroy any jobs or programs that you suspended and are unable to restart
kill
This displays text files, one screen at a time
less
This lets you read text without it scrolling quickly off your screen
less
ls
list filenames and directories
This makes a link to a file
ln
This sends files to printers
lpr
Displays information about one or more files
ls
This lists all of the files within a directory and its subdirectories that match a set of conditions
ls
To list the permissions on files, which of the following commands will work?
ls -l
To output only the permissions of the files in the working directory, which of the following commands will do it?
ls -l | cut -c2-10
Count the files that you own in all your directories (where your userid is myusername)
ls -lR | grep myusername | wc -l
To match all your .files (that is, any hidden files begins with a period).
ls .*
To list filenames where the first two characters can be any character, followed by an 'R', followed by any string:
ls ??R*
To match filenames that start with 'CPP', followed by any two characters, followed by any non-digit string:
ls CPP??[!0-9]*
To match filenames that start with 'CPP', where the next two characters can be anything, but the next character must be a '1':
ls CPP??[1]
To match only numbered filenames use:
ls [0-9]*
To match filenames starting with an upper case letter only:
ls [A-Z]*
To match filenames starting with a lower case letter only:
ls [a-z]*
To list all filenames that start with an 'i' or 'o':
ls [io]*
To match all filenames that start with 'f', followed by any two characters, followed by any string; the end character must be an 's':
ls f??*s
To list all filenames (log followed by some string) but with no numbers.
ls log.[!0-9]*
To match filenames that begin with 'log.', followed by a single number, followed by any character (including none).
ls log.[0-9]*
Mail utility that POSIX requires all unix systems to support is
mailx
Which command/tool is used for building and maintaining groups of programs from source code?
make
mkdir
make a directory
How do you get help about the command "cp"?
man cp
Which command is used to create the directory "abc" in the previous (parent) directory?
mkdir ../abc
How do you create a new directory called "flower"?
mkdir flower
Creates a filesystem on a device
mkfs
In Unix, if you wanted to allow a user to modify file permissions in a directory, you would give the directory what permission?
modify
This displays the contents of a file one screen at a time, waiting for you to press the Spacebar between screens
more
Which of the following is not a benefit of the fact that many UNIX commands operate on plain ASCII text files? the same file can be used by many programs output to the terminal and to files can be done in the same way most current UNIX installations have a graphical user interface these commands can be used as filters for the output of other commands
most current UNIX installations have a graphical user interface
mv
move a file to another location
Renames or moves a file
mv
To rename the file "a.html" to "b.html", which command do you use?
mv -i a.html b.html
How do you rename file "new" to be "old"?
mv new old
Changes the priority of a command
nice
Numbers lines from a file
nl
Runs a command that keeps running after you log out
nohup
Sets the specified permissions to those of others
o
Dumps the contents of a file
od
Opens files, directories, and URLs
open
cat
outputs content of a text file, read through brief files, concatenate files together
A command used for changing user password is
passwd
Joins corresponding lines from files
paste
Creates an archive, restores files from an archive, or copies a directory hierarchy
pax
Which one of the following methods is NOT correct for two processes to communicate each other?
pipe
Which mode of the gdb debugger ascertains the cause of the crash by examining the core files?
post-mortem mode
Process attributes are stored in
process table
ps fetches attributes from
process table
This displays information about programs that are currently running Displays process status
ps
Which of the following commands displays the full pathname of the directory you are currently positioned in?
pwd
Sets read permission
r
In Unix, the octal number "5" corresponds to which ___ file permission.
r - x
In Unix, if you wanted to allow a user to list the contents of a directory, you would give the directory what permission, at least?
read
Changes the priority of a process
renice
To delete a file called mynotes.txt, which command do you use?
rm -i mynotes.txt
Removes directories
rmdir
Securely copies files and directory hierarchies over a network
rsync
Set the user ID or group ID of the file while the file is being executed
s
Securely copies one or more files to or from a remote system
scp
A Command to record your session is
script
Edits a file noninteractively
sed
This displays or changes various settings and options associated with your Unix session
set
Creates a process that sleeps for a specified interval
sleep
Sorts and/or merges files
sort
Divides a file into sections
split
Securely runs a program or opens a shell on a remote system
ssh
Displays information about files
stat
Which command in debugger is used to execute the next statement but descends into a function?
step
What is the default datatype of variables in bash or ksh shell scripts?
string
Displays strings of printable characters from files
strings
Displays or sets terminal parameters
stty
A Command to display current terminal settings is
stty -a
Sets the sticky bit
t
Displays the last part (tail) of a file
tail
Stores or retrieves files to or from an archive file
tar
Copies standard input to standard output and one or more files
tee
Check file types and compare values
test
gzip
the utility compresses files
zcat
the utility displays files compressed with this utility
gunzip
the utility restores files compressed with gzip
The -follow option with find command is ____.
to chase down the source of the files for symbolic linked files
The -name option with find command is ____.
to find files by filename
The -user option with find command is ____.
to find files by user ownership
The -type option with find command is ____.
to find files that are a certain type
The -newer option with find command is ____.
to find files that are newer than one file but older than the other file
The -mtime option with find command is ____.
to find files that were accessed or modified some days ago
The -perm option with find command is ____.
to find files with different access or permission bits on a file
Dynamically displays process status
top
What UNIX command is used to update the modification time of a file and/or change the file's access?
touch
Replaces specified characters
tr
(T/F) Consider a file abc which can be "read, write, execute" only by the owner. After the command "chmod og+rx abc", the file abc executable and readable by all.
true
(T/F) Consider a file abc which can be "read, write, execute" only by the owner. After the following command: "chmod g+x abc", the result will be is equivalent to the result of command: chmod 710 abc.
true
(T/F) Consider a file abc which can be "read, write, execute" only by the owner. The result of the following command "chmod 700 abc" is equivalent to "chmod og-rwx abc"
true
(T/F) Consider a file abc which can be "read, write, execute" only by the owner. The result of the following command "chmod og+rx abc" is equivalent to the command "chmod 755 abc"
true
(T/F) The command "grep hello file" prints all lines in "file" that contains hello.
true
(T/F) The command "ls" lists the contents of a directory.
true
(T/F) UNIX supports a hierarchical directory structure.
true
This command shows which version of a particular command(example: echo) will be executed.
type echo
What is the effect of the command alias up2="cd ../.."?
typing "up2" at a shell prompt takes you up two levels in the directory tree
Sets the specified permissions to those of the owner
u
Specifies the file-creation permissions mask
umask
A Command to get the version or release of your operating system is
uname -r
Displays unique lines from a file
uniq
List the format of the passwd file in order:
username, password, user identifier, group identifier, gecos (comment), home directory, shell
Displays information about local system users
w
If you use this, you also get a list of what they are doing and who is doing it.
w
Sets write permission
w
Displays the number of lines, words, and bytes in one or more files
wc
Shows where in PATH a utility is located
which
Displays information about logged-in users
who
If you use this, you also get the IP numbers or computer names of the terminals they are using.
who
A Command to get your userid is
who am i
^
will match the beginning of the line only
$
will match the end of the line only
Sets execute permission
x
Converts standard input to command lines
xargs
When creating a directory as an ordinary user, what is true?
you must be in your home directory or in one of its subdirectories
When parent process doesn't wait till child's death, the child enters into a
zombie state
