010-160 The Power OF The Command Line Practice Test 4 — 15 Questions

Question 1

Which command is used to display lines of a file that match a pattern, while ignoring case?

Accepted Answer

grep -i. The 'grep -i' option performs a case-insensitive pattern match, so lines containing 'Error', 'error', or 'ERROR' all match a search for 'error'. This is the standard way to search files while ignoring letter case. The -i flag is documented in the grep man page as 'ignore case distinctions in patterns and input data'.

Answer

grep -v

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grep -w

Answer

grep -r

Question 2

How do you check the exit status of the last command executed?

Accepted Answer

echo $?. In POSIX shells (bash, sh, dash), the special parameter $? expands to the exit status of the most recently executed foreground pipeline. A value of 0 conventionally indicates success, while any non-zero value (1-255) signals failure or a specific error condition. This is the standard mechanism scripts use to branch on command success, e.g., 'if [ $? -eq 0 ]; then ...'.

Answer

echo $#

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echo $!

Answer

echo $status

Question 3

To sort the lines of a text file numerically instead of alphabetically, which flag do you use?

Accepted Answer

sort -n. The -n flag tells sort to perform a numeric sort, comparing lines by their numeric value rather than lexicographically. This is essential when sorting numbers like 2, 10, 100, which would otherwise sort as 10, 100, 2 alphabetically.

Answer

sort -f

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sort -u

Answer

sort -r

Question 4

Which TWO of the following are valid commands for displaying file contents?

Accepted Answer

cat. Option A, cat, is correct because the cat command concatenates and prints file contents to standard output, making it a standard way to display a file's contents. Option E, less, is correct because less is a pager that displays file contents one screen at a time and allows scrolling through the file. Option B, touch, is not correct because touch creates empty files or updates file timestamps rather than displaying contents. Option C, chmod, is not correct because chmod changes file permission modes and does not read or display file data. Option D, grep, is not correct because grep searches for and prints matching lines from input or files, which is a filtering operation rather than a general file-content display command.

Answer

touch

Answer

chmod

Answer

grep

Question 5

Which TWO of the following commands can be used to redirect input from a file?

Accepted Answer

cat file | command. Option B (cat file | command) is correct because piping the output of cat file into another command feeds that file's contents to the command's standard input, effectively redirecting input from the file. Option C (<) is correct because the input redirection operator < explicitly redirects a command's standard input to come from a file, as in command < file. The unmarked options do not belong: && is a logical AND operator that conditionally chains commands based on exit status, while > and >> are output redirection operators that send standard output to a file (truncating and appending, respectively), not input.

Answer

&&

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>

Answer

>>

Question 6

Which TWO of the following regex patterns are valid for grep to match the beginning or end of a line?

Accepted Answer

$. Option E, the caret (^), is correct because in grep's basic regular expressions it is the anchor that matches the start of a line, so a pattern like ^root matches lines beginning with 'root'. Option A, the dollar sign ($), is correct because it is the anchor that matches the end of a line, so a pattern like bash$ matches lines ending in 'bash'. Option C, the dot (.), is not an anchor; it matches any single character. Option D, the asterisk (*), is a quantifier meaning zero or more repetitions of the preceding element, not a line anchor. Option B, the backslash (\), is an escape character used to remove the special meaning of the following character, not a beginning- or end-of-line anchor.

Answer

\

Answer

.

Answer

*

Question 7

Which THREE of the following are environment variables commonly seen in a Linux shell?

Accepted Answer

USER. USER is a standard environment variable that holds the username of the currently logged-in user, so option A is correct. HOME is a standard environment variable that specifies the current user's home directory path, making option C correct. PATH is a standard environment variable that lists the directories the shell searches for executable commands, so option E is correct. ROOT (B) is not a standard environment variable; it is a common username or directory name, not a shell variable. FILE (D) is not a standard environment variable either; it is only a special variable inside Makefiles, not a general Linux shell environment variable.

Answer

ROOT

Answer

FILE

Question 8

Which THREE of the following represent ways to manipulate command output in a pipe?

Accepted Answer

grep. grep is correct because it filters piped input line-by-line using pattern matching and emits only matching lines to stdout, which is a classic way to manipulate command output in a pipe. wc is correct because it consumes piped input and produces counts of lines, words, and bytes (with -l, -w, -c), transforming the stream into summary output. sed is correct because it is a stream editor that reads piped input and performs non-interactive text transformations such as substitution (s/old/new/g), deletion, and printing, directly manipulating the output stream. cd is not correct because it is a shell builtin that changes the current working directory and does not read stdin or transform piped data. pwd is not correct because it simply prints the current working directory name and does not accept or manipulate piped input.

Answer

cd

Answer

pwd

Question 9

Which TWO of the following are commands to delete files or directories?

Accepted Answer

rmdir. Option A, rmdir, is correct because it is the standard Linux/Unix command used to remove empty directories from the filesystem. Option B, rm, is correct because it is the standard command for deleting files and, with the -r (recursive) flag, directories and their contents. The other options do not delete anything: ls lists directory contents, cp copies files or directories, and mv moves or renames files or directories without removing them.

Answer

ls

Answer

cp

Answer

mv

Question 10

Which THREE of the following are valid ways to run commands sequentially?

Accepted Answer

;. Option A (;) is correct because the semicolon is the shell's unconditional command separator, so `cmd1 ; cmd2` runs cmd2 after cmd1 finishes regardless of cmd1's exit status. Option D (&&) is correct because the logical AND operator runs the second command only if the first command exits successfully (exit status 0), which is a standard way to chain commands sequentially with dependency. Option E (||) is correct because the logical OR operator runs the second command only if the first command fails (non-zero exit status), also executing commands one after another in sequence. Option B (|) is not a sequential runner but a pipe that connects the standard output of one command to the standard input of another, and both processes typically run concurrently. Option C (>) is a redirection operator that sends standard output to a file, not a command-sequencing construct.

Answer

|

Answer

>

Question 11

Which THREE of the following tools can be used for text processing?

Accepted Answer

awk. awk (A) is a full-featured text-processing language and utility that scans input line by line, splits fields, and performs pattern-action processing, making it a core text-processing tool. grep (B) is a text-processing tool because it searches input streams or files for lines matching a regular expression and prints the matching lines. sed (C) is a stream editor that performs text transformations such as substitution, deletion, and insertion on input streams, so it is also a text-processing tool. The unmarked options do not belong: cat (D) simply concatenates and outputs file contents without transforming or analyzing text, and ls (E) lists directory entries rather than processing text.

Answer

cat

Answer

ls

Question 12

Which TWO of the following help manage compressed archive contents?

Accepted Answer

gzip. Option C, gzip, is correct because it is the standard GNU/Linux compression utility that compresses and decompresses files (creating .gz archives) and can also list compression information with gzip -l, directly managing compressed archive contents. Option E, tar, is correct because it is the archiving utility that bundles multiple files and directories into a single archive and, when combined with compression options such as -z (gzip), -j (bzip2), or -J (xz), creates and extracts compressed archives like .tar.gz, making it a primary tool for managing compressed archive contents. Option A, find, is incorrect because it searches the filesystem for files matching criteria such as name, size, or permissions; it does not compress, decompress, or manipulate archive contents. Option B, cat, is incorrect because it concatenates and displays file contents to standard output and has no archive or compression management capability. Option D, grep, is incorrect because it searches text patterns within files and, while it can search inside uncompressed streams, it does not create, extract, or otherwise manage compressed archives.

Answer

find

Answer

cat

Answer

grep

Question 13

Which THREE of the following are common shell built-in command types?

Accepted Answer

echo. echo (A) is a shell built-in because most shells implement it internally to print arguments to standard output, and it is listed among the shell's built-in commands. cd (B) must be a built-in since changing the current working directory affects the shell process itself, and an external program could not alter its parent shell's directory. export (E) is a built-in because it sets or modifies environment variables in the current shell's environment, which external commands cannot do for the parent shell. grep (C) and tar (D) are external utilities located as separate executables (e.g., /usr/bin/grep, /bin/tar) rather than shell built-ins, so they do not belong.

Answer

grep

Answer

tar

Question 14

Which TWO of the following signals can be used to interact with processes?

Accepted Answer

SIGTERM. SIGTERM (A) is a standard, catchable termination signal (signal number 15) that can be sent to a process with the kill command to request it to shut down gracefully, allowing it to run cleanup handlers before exiting. SIGKILL (B) is signal number 9, an uncatchable and unblockable signal that forcibly terminates a process immediately, making it the other valid way to interact with and control a running process. The remaining options are not real signals: SIGSTOPPED (C) is not a defined signal (the actual stop signal is SIGSTOP, number 19), SIGEXIT (D) does not exist in the standard signal set, and SIGRUN (E) is likewise not a valid signal name.

Answer

SIGSTOPPED

Answer

SIGEXIT

Answer

SIGRUN

Question 15

Which THREE of the following are valid ways to get help on a command?

Accepted Answer

info command. Option C (info command) is correct because GNU Info pages provide detailed, hyperlinked documentation for many commands and utilities, invoked as 'info <command>'. Option D (command --help) is correct because most GNU/Linux commands support the '--help' flag, which prints a concise usage summary and available options directly to standard output. Option E (man command) is correct because the 'man' utility displays the system manual pages for a command, covering its syntax, options, and description. Options A and B are not valid: 'help command' is not a general help mechanism (the 'help' builtin only works for shell builtins, not arbitrary commands), and 'search command' is not a help command at all.

Answer

help command

Answer

search command