LPIC-1 Shells, Scripting and Data Management Practice Test 5 — 15 Questions

Question 1

A system administrator wants to monitor a log file in real-time for lines containing 'ERROR' and write them to a separate file. Which command combination is most appropriate?

Accepted Answer

tail -f logfile | grep 'ERROR' > error.log. `tail -f logfile` continuously outputs new lines appended to the file, and piping that output into `grep 'ERROR'` filters only lines containing 'ERROR', which are then redirected to `error.log`. This combination achieves real-time monitoring and selective logging without blocking the terminal or requiring manual intervention.

Answer

less logfile

Answer

vi logfile

Answer

cat logfile | grep 'ERROR' > error.log

Question 2

Which TWO of the following commands can be used to replace text patterns in a file and output the result?

Accepted Answer

awk. Option A, awk, is correct because awk is a full text-processing language that supports substitution via the gsub() function (e.g., awk '{gsub(/old/,"new"); print}' file), which replaces matching patterns and prints the modified result to standard output. Option C, sed, is correct because sed is the classic stream editor whose s/// substitution command (e.g., sed 's/old/new/g' file) replaces text patterns and writes the transformed content to stdout without altering the original file. Option B, grep, is not correct because grep only searches for and prints lines matching a pattern; it does not replace text. Option D, tr, is not correct because tr translates or deletes individual characters rather than replacing multi-character text patterns. Option E, cut, is not correct because cut extracts selected fields or columns from each line and performs no substitution.

Answer

grep

Answer

tr

Answer

cut

Question 3

Which THREE of the following are types of expansion performed by the bash shell during command parsing?

Accepted Answer

Parameter expansion. Parameter expansion (A) is a genuine bash expansion type: the shell replaces constructs like $var, ${var}, or ${var:-default} with their values during command parsing. Tilde expansion (B) is also a real expansion: a leading ~ is replaced with the current user's home directory (or ~user with that user's home), as in ~/file becoming /home/user/file. Brace expansion (C) is likewise a bash expansion type: patterns such as {a,b,c} or {1..5} are expanded into multiple words before other expansions like parameter and command substitution. Variable assignment (D) is not an expansion but a shell operation that stores a value in a variable, and alias expansion (E) is not one of bash's documented expansion stages; aliases are substituted earlier during tokenization/alias lookup, not as a formal expansion type.

Answer

Variable assignment

Answer

Alias expansion

Question 4

A senior administrator runs a script that processes a CSV file. The script contains the following snippet: 'for field in $(cat data.csv); do ...'. The data.csv file contains lines like: 'John Doe, 123 Main St, Springfield'. The script fails to process correctly, splitting fields incorrectly and causing errors. Which of the following is the most appropriate fix?

Accepted Answer

Use a while loop with read: 'while IFS= read -r line; do ... done < data.csv'. The script fails due to word splitting and globbing when iterating over the output of `cat data.csv` with a `for` loop. Using `while IFS= read -r line` reads each line verbatim, preserving spaces and commas, and is the standard pattern for processing CSV or delimited files line by line in bash.

Answer

Use xargs to process each line

Answer

Use 'for field in $(<data.csv)' with proper quoting

Answer

Use 'for field in "$(cat data.csv)"' with double quotes around the substitution

Question 5

Which TWO of the following are valid ways to capture the output of a command into a variable in Bash?

Accepted Answer

var=`command`. Option A, var=`command`, is correct because backticks are the legacy command-substitution syntax in Bash: the shell runs command in a subshell and replaces the backtick expression with its standard output, which is then assigned to var. Option C, var=$(command), is correct because the modern $(...) form performs the same command substitution, capturing command's stdout into var, and is preferred since it nests more cleanly and avoids backtick escaping issues. Option B, var={command}, is not valid because braces are used for brace expansion (e.g., {a,b}) and parameter expansion (${var}), not command substitution. Option D, var|command, is not valid because it would attempt to pipe the variable name as a command into another command rather than assign output. Option E, var=command, is not valid because it simply assigns the literal string 'command' to var without executing it or capturing any output.

Answer

var={command}

Answer

var|command

Answer

var=command

Question 6

Refer to the exhibit. A user gets this error when running a script. What is the most likely cause?

Accepted Answer

The script has Windows-style line endings (CRLF).. The error message shown in the exhibit (typically '/bin/bash^M: bad interpreter' or similar) indicates that the script contains carriage return characters (CR, \r) at the end of lines, which is characteristic of Windows-style CRLF line endings. When Linux's Bash tries to interpret the shebang line, it sees '/bin/bash^M' as the interpreter path, which does not exist, causing the script to fail. This is a common issue when scripts are created or edited on Windows and then transferred to a Unix-like system without converting line endings.

Answer

The script is missing a shebang line.

Answer

The script does not have execute permission.

Answer

The script contains a syntax error in line 3.

Question 7

A systems administrator maintains a Linux web server running Apache HTTP Server (version 2.4) with three virtual hosts. The server logs are stored in /var/log/httpd/ and are rotated using logrotate, which is configured with the default settings that came with the Apache package. The administrator has noticed that after the nightly log rotation, the main access log file (access_log) is empty, while the rotated log files (e.g., access_log.1, access_log.2) contain the previous day's data. Furthermore, new HTTP requests are being logged into the most recent rotated file (access_log.1) instead of the current access_log file. The administrator has verified that the logrotate cron job runs successfully, and that the log files are owned by the root user with read/write permissions for the root group. No errors appear in the system logs. The Apache service continues to run and serve web pages. Which of the following actions should the administrator take to ensure that Apache writes new log entries to the current access_log file after rotation?

Accepted Answer

Add a postrotate script to the logrotate configuration that sends a USR1 or HUP signal to the Apache process to cause it to reopen the log files.. The issue is that after logrotate moves the current access_log to access_log.1, Apache continues writing to the old file descriptor (now pointing to access_log.1) because it never reopened the log file. Sending a USR1 or HUP signal to Apache causes it to close and reopen its log files, creating a new access_log and writing new entries there. This is the standard method for log rotation with Apache and other daemons that keep file handles open.

Answer

Modify the Apache configuration to set the 'RotateLogs' directive and restart the service.

Answer

Change the logrotate frequency to 'weekly' so that the log is not rotated as often.

Answer

Set the 'copytruncate' directive in the logrotate configuration to copy the log file and truncate the original, so Apache can continue writing without interruption.

Question 8

A user runs the command `echo $HOME` in a Bash shell and receives the output `/home/alice`. A colleague later runs the same command in a different shell and gets `/root`. Which type of shell variable is being displayed?

Accepted Answer

An environment variable. HOME is an environment variable that is exported to child processes, so it is inherited by commands run from the shell. It is set at login time based on the user account, which is why different users see different values. Local variables, positional parameters, and special parameters do not behave this way.

Answer

A local shell variable

Answer

A special shell parameter

Answer

A positional parameter

Question 9

A backup script stores its log file path in the variable LOGFILE and needs to append a timestamp line to that file. Which command correctly appends the output of the `date` command to the file named in the variable?

Accepted Answer

date >> $LOGFILE. Appending output requires the `>>` redirection operator, which opens the destination file for appending rather than truncating it. With the variable expanded to the log path, `date >> $LOGFILE` adds a new timestamp line while keeping all previous entries intact, which is exactly what the backup script needs.

Answer

date < $LOGFILE

Answer

date | $LOGFILE

Answer

date > $LOGFILE

Question 10

A Linux administrator needs to extract all lines from `/var/log/syslog` that contain the word `error` (case-insensitive) and save them to `errors.txt`. Which command accomplishes this?

Accepted Answer

grep -i error /var/log/syslog > errors.txt. The grep command with -i performs a case-insensitive search, and the > redirection writes the matching lines to a file. The other options either invert the match, count matches, or list filenames, none of which produce the desired output of the matching lines themselves.

Answer

grep -c error /var/log/syslog > errors.txt

Answer

grep -v error /var/log/syslog > errors.txt

Answer

grep -l error /var/log/syslog > errors.txt

Question 11

A user wants to set a shell variable named DEPLOY_ENV to the value 'staging' in the current Bash session so that child processes can read it. Which command accomplishes this?

Accepted Answer

export DEPLOY_ENV=staging. To make a variable available to child processes, it must be exported into the environment. The export builtin, used together with an assignment, both sets the variable in the current shell and ensures it is inherited by subsequently launched commands. A plain assignment stays local to the shell, set controls shell options, and env without a command only displays the environment.

Answer

DEPLOY_ENV=staging

Answer

set DEPLOY_ENV=staging

Answer

env DEPLOY_ENV=staging

Question 12

A script needs to read a file line by line, preserving leading and trailing whitespace and backslashes. Which loop construct should be used?

Accepted Answer

while IFS= read -r line; do echo "$line"; done < file.txt. Reading a file line by line while preserving exact content requires disabling both word splitting and backslash processing. Clearing IFS stops the shell from trimming leading and trailing whitespace, and the -r option stops backslash escapes from being interpreted. Using only one of these settings leaves the other behavior active and alters the data.

Answer

while read line; do echo "$line"; done < file.txt

Answer

while read -r line; do echo "$line"; done < file.txt

Answer

for line in $(cat file.txt); do echo "$line"; done

Question 13

A system administrator runs a script that contains the line: trap 'echo "Cleaning up..."' EXIT. The script is executed and then receives SIGINT (Ctrl+C) before normal completion. What happens?

Accepted Answer

The trap on EXIT is executed because SIGINT causes the shell to exit.. The EXIT trap runs when the shell exits, regardless of whether the exit is normal or caused by a signal that terminates the shell. When SIGINT is received and not otherwise trapped, the shell exits, triggering the EXIT trap before termination. This makes EXIT suitable for cleanup actions such as removing temporary files.

Answer

The trap on EXIT is ignored because the script was interrupted by a signal.

Answer

The trap on EXIT is executed only if the script completes normally.

Answer

The script continues running because SIGINT is trapped and ignored by default.

Question 14

A script uses the command substitution: files=$(ls). Which statement about the resulting value of files is true?

Accepted Answer

The variable files contains the output of ls, with trailing newlines removed.. Command substitution captures the standard output of the enclosed command and removes trailing newline characters. Internal newlines are retained, but the final newline is stripped. This behavior is consistent across shells and is why using the result unquoted can lead to word splitting on spaces, tabs, and newlines.

Answer

The variable files contains the output of ls with newlines replaced by spaces.

Answer

The variable files contains the exit status of the ls command.

Answer

The variable files contains a list of filenames separated by null characters.

Question 15

An administrator needs to extract only the fifth field from a colon-delimited file, but some lines contain fewer than five fields and must be skipped rather than printed as empty. Which awk program accomplishes this?

Accepted Answer

awk -F: 'NF >= 5 {print $5}' file. The requirement is to skip records that lack a fifth field, which is exactly what the NF field-count variable expresses. Testing NF >= 5 before printing $5 rejects short lines at the source, whereas tests on the value or length of $5 conflate an absent field with a present-but-empty one and can silently drop legitimate empty fields. Using NF keeps the decision tied to the record's structure.

Answer

awk -F: '$5 != "" {print $5}' file

Answer

awk -F: '{print $5}' file | grep -v '^$'

Answer

awk -F: 'length($5) > 0 {print $5}' file