Linux Questions & Answers – Search Pattern

This set of Linux / Unix questions and answers focuses on string search operations & pattern matching commands. It will be useful for anyone learning Linux Basics, Essentials and/or Administration.

1. Which option of grep displays the line number as well?
a) -v
b) -l
c) -n
d) -E
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2. How can you search for blank line in a file?
a) $ grep “ “ file
b) $ grep “^$” file
c) $ grep [“ “] file
d) $ grep [^$] file
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3. Assuming the files fileA, fileB, fileAB, fileBC and fileABC, exist in a directory, which files match with the pattern file[ABC]?
a) fileA, fileB and fileABC
b) fileABC
c) fileA and fileB
d) fileAB, fileBC and fileABC
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4. What will be printed for the command below?
$ grep –c “^echo” abc
a) The count of lines that do not contain the pattern echo in file abc
b) The count of lines which begin with the pattern echo in file abc
c) The count of lines that ends with the pattern echo in file abc
d) None of the mentioned
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5. Which one is used to select only one copy of the repeated lines?
a) uniq -u
b) uniq -d
c) uniq -c
d) uniq –I
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6. Indicate the right option to search for BOB, Bob, BOb or BoB?
a) grep –i Bob files
b) grep ‘B[oO][bB]’ files
c) grep ‘[BOB]’ files
d) grep -v ‘Bob’ files
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7. Indicate the right option to search for anything not a letter or number
a) grep ‘^[a-zA-Z0-9]’
b) grep ‘[^a-zA-Z0-9]’
c) grep ‘[a-zA-Z0-9]’
d) None of the mentioned
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8. How do you remove duplicate lines from the file foo using uniq?
a) sort foo | uniq –u
b) sort -u foo | uniq -d
c) sort foo | uniq –c
d) sort foo | uniq –I
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9. One of the entry of /etc/passwd file is shown below:
user1:x:1111:2222:Sanfoundry:/home/user1:/bin/bash
Which among the following will print userid and home dir in the following pattern “user1:/home/user1”
a) awk `{print $1 “:” $6}` /etc/passwd
b) awk `{print $1 “:” $7}` /etc/passwd
c) awk `{print $2 “:” $6}` /etc/passwd
d) awk `{print $2 “:” $7}` /etc/passwd
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10. who | cut –d ” ” -f1
what is the ouput if the who command displays like this
user1 tty 0 1234
a) user1
b) user1 tty 0 1234
c) tty
d) tty 0 1234
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11. What is the command that can print lines of first file matching with second file?
a) printline
b) cmp
c) com
d) comm
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12. Which character to use to escape meaning of special characters in search operations?
a) []
b) ^
c) .
d) backslash (\)
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Sanfoundry Global Education & Learning Series – Linux Administration & Programming.

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