Pattern matching, Question 1 In sed, when you do pattern

Pattern matching

Reference no: EM13168147

Question 1

In sed, when you do pattern matching, the largest pattern is always matched first, left to right.

True or False

Question 2

If shell script has owner, group, and others (world) execute permissions set but only read permissions set for group and others, this script can be executed by the owner.

True or False

Question 3

The command
cd /; tar cf - etc | ( cd /tmp ;tar -xf - )
copies the contents of /etc into /tmp

True or False

Question 4

The command
tr 'a-z' 'A-Z' | tr 'A-Z' 'a-z'
translates all lower case letters to upper case and all upper case letters to lower case.
After the command is run, case of the input stream will be swapped.

True or False

Question 5

The command
grep -iw shell | wc -l
correctly counts the number of times the text shell appears in the standard input stream.

True or False

Question 6

The command

echo "This is a message" 2>&1

writes its output "This is a message" to standard error.

True or False

Question 7

The command

cut -d: -f1 | more < /etc/passwd

would correctly print the first field of the password file and send the results to the program more.

True or False

Question 8

The command:

tr -d '\012'

removes the newline from the input stream

True or False

Question 9

The command

grep '^

file | wc -l

count all the lines in a file which are empty.

True or False

Question 10

The command

sort +2 -3 names

Sorts the file names on the third word.

True or False

Question 11

The command

ls | paste - -

lists all files in the current directory in three columns

True or False

Question 12

The uniq command will remove duplicate consecutive lines.

True or False

Question 13

Running the command

sort -u

is always the same as running the command

uniq

True or False

Question 14

The command

sed 's/a/b/g'

produces the same output as running the command

sed 's;a;b;g'

True or False

Question 15

The command
sed 's/a/&&/g'

doubles only the first occurance of 'a' on each line processed.

True or False

Question 16

Unquoted $@ and $* evaluate to the same thing

True or False

Question 17

Changes which a child process makes to the environment do effect its parents environment. For example, If a child process changes and environment variable, that change happens in the parent process.

True or False

Question 18

Changes which the parent makes to the environment after the child is created, do not effect the child's environment.

True or False

Question 19

Note, If field 7 of the password file is empty, it is assumed to be /bin/sh. Which of the following commands count the number of users whose login shell is /bin/sh? (Remember the rule from above.)

a. ( grep ':

/etc/passwd; grep ':/bin/sh

/etc/passwd) | wc -l

b. sed 's,:$,:/bin/sh,' /etc/passwd | grep ':/bin/sh

| wc -l

c. egrep -ce ':$|:/bin/sh

/etc/passwd

d. A & B & C

e. A & B

Reference no: EM13168147

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