Unix Exam 1
[Sobell] 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
[Unix&Shell1] This "find" command option will go and look at all the files first before hitting any of the directories or sub-directories.
-depth
The figure below shows a sample of ____ file. oracle:x:1021:1020:oracle user:/data/network/oracle:/bin/bash
/etc/passwd
[Sobell1-4] Which of the following 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
[Sobell] 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
[Sobell] With this option of chmod command, Owner can read, and write the file; group and other can read the file.
0644
[Sobell] With this option of chmod command, Owner can read, write, and execute the file; group and other can execute the file.
0711
[Sobell] With this option of chmod command, Owner can read, write, and execute the file; group and other can read and execute the file.
0755
[Sobell] With this option of chmod command, Owner, group, and others can read, write, and execute the file.
0777
[Korn08] PID of init process is ___
1
[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
1
Sticky bit
1000
[Korn08] Consider the following program code. How many times will it output "Hello"? main() { fork( ); fork( ); fork( ); fork( ); printf("Hello"); }
16
[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 '[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
[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 '^[^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
[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 '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
[Korn08] 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
* (an asterisk symbol)
A single character followed by an *, will match zero or more occurrences.
[Korn08] This points out the one which is not a section of "man" page.
BRIEF
[Sobell1-4] Which of the following is not a UNIX file type?
Batch file
[Korn08] What is not an advantage or a feature of CVS?
CVS can manage well a complex distributed source control
chmod
Change file security setting.
[Sobell1-4] 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
cd
Change to another directory.
[ ] (a square-bracket open-close symbol)
Character enclosed inside it will be matched. One can use the - to include a range inclusively.
rmdir
Delete a directory.
rm
Delete a file.
pwd
Display current working directory - i.e. where am I?
[Sobell1-4] The file "assign4.html" has permissions set as: "r w x r w x r w x". This means that:
Everyone can read, write, and execute the file.
[Sobell1-4] (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
[Sobell1-4] (T/F) The command "grep -i hello" prints all the lines in file, not containing the string "hello".
False
[Sobell1-4] (T/F) The command pwd is normally used to change the password.
False
[Sobell1-4] The command history prints ALL the commands you typed.
False
[Unix&Shell1] _____ is a very powerful tool and command, searching through the system or just current directory, locating all or certain files or directories.
Find
man
Help manual.
[Korn08] If a program executing in background attempts to read from the default STDIN (that is, keyboard), then ____
Its execution will be suspended.
ls
List filenames and directories.
. (a dot symbol)
Matching any single character.
[Korn08] What is the output of the below code? void exit_handler1(); void exit_handler2(); int main() { int pid; atexit(exit_handler1); atexit(exit_handler2); pid = fork(); if(pid == 0) { _exit(0); } else { sleep(2); exit(0); } return 0; }
Only parent executes the exit_handler1 and exit_handler2.
[Sobell1-4] Which of these expressions shows the proper way to add the directory /usr/bin to your path?
PATH=$PATH:/usr/bin
[Korn08] Which mode of the gdb debugger ascertains the cause of the crash by examining the core files?
Post-mortem mode
[Korn08] Which of the following signals cannot be handled or ignored?
SIGKILL
[Korn08] Default action of SIGSEGV is _____
Start Core dump
[Korn08] Which of the following values for STAT (status) column of ps command is NOT correct?
Status E means exited
[Sobell] ____ Displays strings of printable characters from files
Strings
[Sobell1-4] (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
[Sobell1-4] (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
[Sobell1-4] (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
[Sobell1-4] (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
[Sobell1-4] (T/F) The command "grep hello file" prints all lines in "file" that contains hello.
True
[Sobell1-4] (T/F) The command "ls" lists the contents of a directory.
True
[Sobell1-4] (T/F) UNIX supports a hierarchical directory structure.
True
\ (a back-slash symbol)
Use this to escape the special meaning of a metacharacter.
{n}
Use this to match a specific number of occurrences specified by n that contains the preceding pattern
{n,m}
Use this to match any number of occurrences between n and m of the preceding pattern.
{n,}
Use this to match at 'least' n occurrence of the preceding pattern.
^ (a cap/caret symbol)
Will match the beginning of the line only.
$ (a dollar symbol)
Will match the end of the line only.
[Sobell1-4] In Unix, if you wanted to allow a user to delete a file, you would give the file the what permission?
Write
[Sobell1-4] In Unix, if you wanted to allow a user to modify file permissions in a directory, you would give the directory what permission?
Write
Make the file executable only if it is a directory
X
[Korn08] A Graphical User Interface supported by every Unix system is generally known as ____.
X Windows
[Sobell1-4] When creating a directory as an ordinary user, which of the following is true?
You must be in your home directory or its subdirectories.
[[:digit:]]
[0-9]
[[:alnum:]]
[0-9a-zA-Z]
[[:upper:]]
[A-Z]
[[:alpha:]]
[a-zA-Z]
[[:lower:]]
[a-z]
[Korn08] A new line (in echo) will be done with this ___.
\n
[Sobell1-4] When you use the ln command, which of the following occurs?
a file is created that points to an existing file
[Shell] What is a shell in UNIX?
a program through which users can issue commands to UNIX
[[:space:]]
a space or a tab
[Korn08] Mark one (of the choices below) which is not a help facility.
about
[Korn08] Which command option (of ar command) is used to add a file to the library?
ar -r
[Sobell] This will print a calendar for a specified month and/or year.
cal
[Sobell] This outputs the contents of a text file. You can use it to read brief files or to concatenate files together.
cat
[Sobell1-4] 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]
[Sobell1-4] 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
[Sobell] This changes your current directory location.
cd
[Sobell1-4] Change the current directory to /usr/local/bin
cd /usr/local/bin
[Sobell] This changes the permission information associated with a file.
chmod
[Sobell1-4] 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
[Sobell] This displays the differences between two files on a byte-by-byte basis.
cmp
[Korn08] Which command is used to check out the files in RCS?
co -l
[Korn08] The delimiter (to separates one piece of path name from other path name) in PATH variable is ___
colon (":")
[Sobell] This compares sorted files
comm
[Sobell1-4] What is the generic syntax for all UNIX commands?
command name, followed by options, followed by arguments
[Korn08] Which command is used to update the files in CVS?
commit
[Sobell] This configures the source code automatically.
configure
cp
copy a file.
[Sobell] This copies a file, preserving the original and creating an identical copy.
cp
[Sobell1-4] Make a copy of file "upper" in the directory two levels up
cp upper ../..
[Sobell] This creates an archive, restores files from an archive, or copies a directory hierarchy.
cpio
[Sobell] This selects characters or fields from input lines and writes them to standard output.
cut
[Korn08] Which is NOT a version control tool used in UNIX?
cygwin
[Sobell] This displays the current day, date, time, and year.
date
[Korn08] To show only the current month-name is: ____
date +%h
[Sobell] For each mounted file system, this reports the file system device, the number of blocks, the number of blocks available, and the directory where the file system is mounted.
df
[Sobell] This reports file system disk usage (i.e., the amount of space taken up on mounted file systems).
df
[Korn08] Which command is used to display lines of source code in gdb debugger?
display
[Sobell] This reports disk usage (i.e., the amount of space taken up by a group of files).
du
[Korn08] 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`"
[Korn08] 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"
[Sobell] This (utility) evaluates an expression and sends the result to standard output.
expr
[Sobell] This displays the classification of a file
file
[Sobell] This is most commonly used to find all of the files that have a certain name.
find
[Unix&Shell1] This ___ is to find all '*.txt' files in the current directory you are in and any sub-directories,
find . -name "*.txt" -print
[Unix&Shell1] 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
[Unix&Shell1] To find files that are over 10 blocks in length (that's 512 bytes a block) use:
find . -size +10 -print
[Unix&Shell1] To find files that are over 10 bytes in length using the character format use:
find . -size +10c -print
[Unix&Shell1] To find files in /var/adm directory that have not been modified in the last five days:
find / -mtime +5 -print
[Unix&Shell1] To find all files that have been modified in the last five days:
find / -mtime -5 -print
[Unix&Shell1] This find command does find all the ordinary files and then test each file for its type.
find / -type f -print | xargs file
[Unix&Shell1] 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
[Unix&Shell1] To find all files but not directories in /etc
find /etc !-type d -print
[Unix&Shell1] 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" {} \;
[Unix&Shell1] To find all directories in /etc
find /etc -type d -print
[Unix&Shell1] To find all symbolic linked files in /etc:
find /etc -type l -print
[Unix&Shell1] 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 {} \;
[Sobell] This utility displays the usernames of users, together with their full names, terminal device numbers, times they logged in, and other information.
finger
[Korn08] ___ creates a process by spawning a process.
fork
[Sobell1-4] Which of these is not a common UNIX shell discussed in class (or textbook or lecture)?
fresh
[Sobell] 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
[Sobell] This ___ will compile C and C++ programs
gcc
[Sobell] This searches for a pattern in files
grep
[Sobell1-4] What is the command to search all files in your current directory for the word "hello"?
grep hello *
The figure below shows a sample of a passwd file. The field #4 is _____.
group identifier
[Sobell] The ___ utility compresses files, the ___ utility restores files compressed with gzip, and the ___ utility displays files compressed with this utility.
gzip, gunzip, zcat
[Sobell] This displays the beginning of a file
head
[Sobell1-4] How do you print the first 15 lines of all files ending by ".txt"?
head -15 *.txt
[Sobell1-4] The figure below shows a sample of a passwd file. The field #6 is _____.
home directory
[Korn08] A user issues the following command sequence: $ a.out & $ bash $ a.out & If the user kills the bash process, then which of the following is true?
init process becomes parent of second a.out process
[Sobell] This reports any programs that you suspended and still have running or waiting in the background (if you had pressed Ctrl-z to suspend an editing session, for example).
jobs
[Sobell] This joins lines from two files based on a common field
join
[Sobell] This terminates a process by PID
kill
[Sobell] Use This as a last resort to destroy any jobs or programs that you suspended and are unable to restart.
kill
[Sobell] This displays text files, one screen at a time
less
[Sobell] This lets you read text without it scrolling quickly off your screen.
less
[Sobell] This makes a link to a file
ln
[Sobell] This sends files to printers
lpr
[Sobell] This lists all of the files within a directory and its subdirectories that match a set of conditions.
ls
[Sobell] This will list the files and the subdirectories in a directory.
ls
[Sobell] ___ Displays information about one or more files
ls
[Sobell1-4] To list the permissions on files, which of the following commands will work?
ls -l
[Sobell] 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
[Sobell1-4] Count the files that you own in all your directories (where your userid is myusername).
ls -lR | grep myusername | wc -l
[Unix&Shell2] To match all your .files (that is, any hidden files begins with a period).
ls .*
[Unix&Shell2] To list filenames where the first two characters can be any character, followed by an 'R', followed by any string:
ls ??R*
[Unix&Shell2] To match filenames that start with 'CPP', followed by any two characters, followed by any non-digit string:
ls CPP??[!0-9]*
[Unix&Shell2] 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]
[Unix&Shell2] To match only numbered filenames use:
ls [0-9]*
[Unix&Shell2] To match filenames starting with an upper case letter only:
ls [A-Z]*
[Unix&Shell2] To match filenames starting with a lower case letter only:
ls [a-z]*
[Unix&Shell2] To list all filenames that start with an 'i' or 'o':
ls [io]*
[Unix&Shell2] 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
[Unix&Shell2] To list all filenames (log followed by some string) but with no numbers.
ls log.[!0-9]*
[Unix&Shell2] To match filenames that begin with 'log.', followed by a single number, followed by any character (including none).
ls log.[0-9]*
[Korn08] Mail utility that POSIX requires all unix systems to support is ____.
mailx
[Korn08] Which command/tool is used for building and maintaining groups of programs from source code?
make
[Sobell] ____ Keeps a set of programs current (to compile, link edit, clean, etc).
make
mkdir
make directory.
[Sobell] ___ Displays documentation for utilities
man
[Sobell1-4] How do you get help about the command "cp"?
man cp
[Sobell] This will make a new subdirectory.
mkdir
[Sobell] ___Creates a directory
mkdir
[Sobell1-4] Which command is used to create the directory "abc" in the previous (parent) directory?
mkdir ../abc
[Sobell1-4] How do you create a new directory called "flower"?
mkdir flower
[Sobell] ___Creates a filesystem on a device
mkfs
[Sobell] This displays the contents of a file one screen at a time, waiting for you to press the Spacebar between screens.
more
[Sobell1-4] Which of the following is not a benefit of the fact that many UNIX commands operate on plain ASCII text files?
most current UNIX installations have a graphical user interface
mv
move a file to another location.
[Sobell] This will move a file.
mv
[Sobell] ___Renames or moves a file
mv
[Sobell1-4] To rename the file "a.html" to "b.html", which command do you use?
mv -i a.html b.html
[Sobell1-4] How do you rename file "new" to be "old"?
mv new old
[Sobell] ___ Changes the priority of a command
nice
[Sobell] ___ Numbers lines from a file
nl
[Sobell] ___ Runs a command that keeps running after you log out
nohup
Sets the specified permissions to those of others
o
[Sobell] ___ Dumps the contents of a file
od
[Sobell] ___ Opens files, directories, and URLs
open
[Korn08] A Command used for changing user password is ____.
passwd
[Sobell] ___ Joins corresponding lines from files
paste
[Sobell] ___ Creates an archive, restores files from an archive, or copies a directory hierarchy
pax
[Korn08] Which one of the following methods is NOT correct for two processes to communicate each other?
pipe
[Korn08] Process attributes are stored in ___
process table
[Korn08] ps fetches attributes from ___
process table
[Sobell] This displays information about programs (i.e., processes) that are currently running.
ps
[Sobell] ___ Displays process status
ps
[Sobell1-4] 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
[Sobell1-4] 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
[Korn08] The priority of a running process can be changed using ____.
renice
[Sobell] ___ Changes the priority of a process
renice
[Sobell] This will remove (delete) a file.
rm
[Sobell] ___ Removes a file (deletes a link)
rm
[Sobell1-4] To delete a file called mynotes.txt, which command do you use?
rm -i mynotes.txt
[Sobell] This will remove (delete) a subdirectory.
rmdir
[Sobell] ___ Removes directories
rmdir
[Sobell] ___ 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
[Sobell] ___ Securely copies one or more files to or from a remote system
scp
[Korn08] A Command to record your session is ____.
script
[Sobell] ___ Edits a file noninteractively
sed
[Sobell] This displays or changes various settings and options associated with your Unix session.
set
The figure below shows a sample of a passwd file. The field #7 is _____.
shell
[Sobell] ___ Creates a process that sleeps for a specified interval
sleep
[Sobell] ___ Sorts and/or merges files
sort
[Sobell] ____ Divides a file into sections
split
[Sobell] ___ Securely runs a program or opens a shell on a remote system
ssh
[Sobell] ___ Displays information about files
stat
[Korn08] Which command in debugger is used to execute the next statement but descends into a function?
step
[Sobell1-4] What is the default datatype of variables in bash or ksh shell scripts?
string
[Sobell] ___ Displays or sets terminal parameters
stty
[Korn08] A Command to display current terminal settings is ____.
stty -a
Sets the sticky bit
t
[Sobell] ___ Displays the last part (tail) of a file
tail
[Sobell] ___ Stores or retrieves files to/from an archive file
tar
[Sobell] ___ Copies standard input to standard output and one or more files
tee
[Sobell] ___ Check file types and compare values
test
[Unix&Shell1] The -follow option with find command is ____.
to chase down the source of the files for symbolic linked files
[Unix&Shell1] The -name option with find command is ____.
to find files by filename
[Unix&Shell1] The -user option with find command is ____.
to find files by user ownership
[Unix&Shell1] The -type option with find command is ____.
to find files that are a certain type
[Unix&Shell1] The -newer option with find command is ____.
to find files that are newer than one file but older than the other file
[Unix&Shell1] The -mtime option with find command is ____.
to find files that were accessed or modified some days ago
[Unix&Shell1] The -perm option with find command is ____.
to find files with different access or permission bits on a file
[Korn08] Which command is used to display (and update) a dynamic list of currently running processes of a system in real-time?
top
[Sobell] ___ Dynamically displays process status
top
[Sobell1-4] What UNIX command is used to update the modification time of a file?
touch
[Sobell] ___ Creates a file or changes a file's access and/or modification time
touch
[Sobell] ___ Replaces specified characters
tr
[Korn08] This command shows which version of a particular command(example: echo) will be executed.
type echo
[Sobell1-4] 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
[Sobell] ___ Specifies the file-creation permissions mask
umask
[Korn08] A Command to get the version or release of your operating system is ____.
uname -r
[Sobell] ____ Displays unique lines from a file
uniq
[Sobell1-4] The figure below shows a sample of a passwd file. The field #3 is _____.
user identifier
Sets write permission
w
[Sobell] If you use this, you also get a list of what they are doing.
w
[Sobell] This lists all users logged into the computer.
w
[Sobell] ____ Displays information about local system users
w
[Sobell] ___ Displays the number of lines, words, and bytes in one or more files
wc
[Sobell] ___ Shows where in PATH a utility is located
which
[Sobell] If you use this, you also get the IP numbers or computer names of the terminals they are using.
who
[Sobell] ___ Displays information about logged-in users
who
[Korn08] A Command to get your userid is ____.
who am i
Sets execute permission
x
[Sobell] ____ Converts standard input to command lines
xargs
[Korn08] When parent process doesn't wait till child's death, the child enters into ____
zombie state