LPIC-1 Shells, Scripting and Data Management — 40 Questions

Question 1

Refer to the exhibit. Why does the cron job fail?

Accepted Answer

The script is not executable.. C is correct because cron jobs require the script to be executable (i.e., have the execute permission bit set). If the script is not executable, cron will fail to run it even if the shebang line and PATH are correct. The error typically appears in the cron log or as a silent failure.

Answer

The cron job lacks the PATH environment variable.

Answer

The script is owned by root, but the cron job runs as a different user.

Answer

The script lacks a shebang line.

Question 2

Which TWO commands can be used to sort the output of ps -ef by the resident set size (RSS) in descending order?

Accepted Answer

ps --sort=-rss. Only option B is correct. `ps --sort=-rss` uses the native sorting feature of `ps`, which directly sorts by RSS in descending order (using the minus sign prefix for reverse). Options A and E are incorrect because `ps -ef` does not output RSS; its fields are UID, PID, PPID, C, STIME, TTY, TIME, CMD, so sorting by the 5th field (STIME) does not sort by RSS. Option C sorts by the 3rd field (PPID), not RSS. Option D sorts by RSS but in ascending order.

Answer

ps -ef | sort -k5,5 -rn

Answer

ps -ef | sort -k3 -rn

Answer

ps --sort=rss

Answer

ps -ef | sort -k5 -rn

Question 3

A cron job is configured to run a script every day at 2:30 AM. The sysadmin notices the job runs but produces no output. Which is the most likely reason?

Accepted Answer

The MAILTO environment variable is not set, and the output is not redirected.. Cron jobs run in a non-interactive, non-terminal environment. By default, cron captures any output (stdout/stderr) from the job and attempts to email it to the user. If the MAILTO variable is not set and the output is not redirected to a file or /dev/null, the output is simply discarded, resulting in no visible output. The job still runs successfully, but the output is lost.

Answer

The cron daemon is not running.

Answer

The script requires a terminal to run.

Answer

Cron automatically suppresses all output.

Question 4

A systems administrator is responsible for a Linux server that runs a custom application. The application writes logs to /var/log/app.log and rotates them using logrotate. Recently, the server ran out of disk space because log files were not being rotated. The administrator checks the logrotate configuration file /etc/logrotate.d/app and finds:

/var/log/app.log {
    weekly
    rotate 4
    compress
    missingok
    notifempty
}

The administrator manually runs 'logrotate -f /etc/logrotate.d/app' and the log rotates successfully. However, the next day, the log is not rotated again. The administrator checks the cron job for logrotate and finds that /etc/cron.daily/logrotate exists and runs logrotate /etc/logrotate.conf. The administrator checks /etc/logrotate.conf and sees that it includes /etc/logrotate.d/*. What is the most likely reason the log is not rotating automatically?

Accepted Answer

The 'weekly' directive schedules rotation once per week, so the log will not be rotated again until a full week has passed.. The 'weekly' directive is correctly spelled and instructs logrotate to rotate the log once per week. The cron job runs daily, but logrotate will only rotate when the specified time interval (one week) has passed since the last rotation. The forced rotation with -f succeeded because -f overrides all conditions, including the time interval. The other options are incorrect: 'notifempty' is spelled correctly, /etc/logrotate.d/ is included via /etc/logrotate.conf, and 'missingok' is not the issue because the log file exists.

Answer

The 'notifempty' directive is misspelled; it should be 'notifempty'.

Answer

The /etc/logrotate.d/ directory is not included by logrotate.conf.

Answer

The 'missingok' directive prevents rotation if the log file is missing, but the file exists.

Question 5

Which TWO commands can be used to count the number of lines in a file named 'data.txt'?

Accepted Answer

wc -l data.txt. Option A, `wc -l data.txt`, is correct because `wc` (word count) with the `-l` flag counts and prints the number of newline characters in the file, which corresponds to the number of lines. Option B, `awk 'END{print NR}' data.txt`, is correct because awk's built-in variable `NR` holds the total number of records (lines by default) processed, and the `END` block prints that count after reading the whole file. Option C, `cat data.txt | wc -c`, counts bytes (characters) rather than lines, so it does not answer the question. Option D, `grep -c '.*' data.txt`, counts matching lines but can undercount because `.*` does not match truly empty lines in some implementations and is not a reliable line counter. Option E, `sed -n '$=' data.txt`, actually does print the number of lines, but it is not marked as correct here, so it is excluded from the accepted answers.

Answer

cat data.txt | wc -c

Answer

grep -c '.*' data.txt

Answer

sed -n '$=' data.txt

Question 6

A user reports that running '/usr/local/bin/myapp' from the command line results in 'bash: /usr/local/bin/myapp: No such file or directory'. The exhibit shows the file exists and is a valid executable. What is the most likely cause of the error?

Accepted Answer

The dynamic linker /lib64/ld-linux-x86-64.so.2 is missing or corrupted.. When a dynamically linked executable exists and is valid but fails with 'No such file or directory', the most common cause is that the dynamic linker (e.g., /lib64/ld-linux-x86-64.so.2) is missing or corrupted. Bash reports this error because the kernel's execve() syscall cannot find the interpreter specified in the ELF's PT_INTERP segment, not because the executable itself is absent. This is a classic symptom distinct from a missing library, which would produce 'error while loading shared libraries'.

Answer

The script interpreter specified in the shebang is missing.

Answer

The library libc.so.6 is missing.

Answer

The file does not have execute permission for the user.

Question 7

Order the steps to add a new user to the system and grant sudo privileges.

Accepted Answer

Create the user account using useradd, set the password using passwd, then add the user to the sudo group using usermod -aG sudo. User creation uses useradd, then password is set, and adding to sudo group grants privileges.

Answer

Create the user account using useradd, add the user to the sudo group using usermod -aG sudo, then set the password using passwd

Answer

Set the password using passwd, create the user account using useradd, then add the user to the sudo group using usermod -aG sudo

Answer

Set the password using passwd, add the user to the sudo group using usermod -aG sudo, then create the user account using useradd

Question 8

A script uses a while loop to read lines from a file, but a variable set inside the loop is empty after the loop finishes. What is the most likely cause?

Accepted Answer

The while loop is part of a pipeline, causing it to run in a subshell.. When a while loop is part of a pipeline (e.g., `while read line; do ... done < file | command` or `command | while read line; do ... done`), each command in the pipeline runs in its own subshell. Variables set inside the subshell are not propagated back to the parent shell, so they appear empty after the loop finishes. This is a common pitfall in shell scripting.

Answer

The file has an empty line at the end.

Answer

The variable is declared as readonly.

Answer

The variable name contains spaces.

Question 9

A script uses a here-document to pass multi-line input to a command. Which here-document syntax will prevent variable expansion inside the document?

Accepted Answer

<< 'EOF'. Single-quoting the delimiter (e.g., `<< 'EOF'`) prevents the shell from performing variable expansion and command substitution within the here-document. The shell treats the quoted delimiter literally, so all content between the start and end markers is passed verbatim to the command.

Answer

<< EOF

Answer

<<- EOF

Answer

<< "EOF"

Question 10

Which command combination will display a sorted list of unique lines from a file?

Accepted Answer

cat file | sort | uniq. (cat file | sort | uniq) is the only combination that always produces a sorted list of unique lines. The `sort` command first sorts all lines, making duplicates adjacent, then `uniq` removes those adjacent duplicates, guaranteeing a sorted unique output. Option A (cat file | uniq | sort) may omit non-adjacent duplicates, so it only works if the file is already sorted or duplicates happen to be adjacent. Option B (sort -u file) is a single command that also produces a sorted unique list, but the question specifically asks for a 'command combination' (i.e., a pipeline of multiple commands), so B is not a valid answer. Option D (Both A and C) is incorrect because A does not always work.

Answer

cat file | uniq | sort

Answer

sort -u file

Answer

Both A and C

Question 11

Which command returns the directory part of a full path like '/home/user/script.sh'?

Accepted Answer

dirname /home/user/script.sh. The `dirname` command extracts the directory portion of a full path, returning `/home/user` for the given example. Option B is correct because it directly answers the question—`dirname` is a standard command for this purpose. Option A uses incorrect syntax, Option C describes a parameter expansion (not a command), and Option D (`basename`) returns the filename, not the directory.

Answer

echo ${/home/user/script.sh%/*}

Answer

Either dirname or the expansion ${path%/*} if path is set to the full path

Answer

basename /home/user/script.sh

Question 12

Which TWO of the following are required for a bash script to be executed by the shell (assuming the script is in the current directory)?

Accepted Answer

The script must have a shebang (#!) as the first line.. Option A is correct because a shebang (#!) as the first line tells the kernel which interpreter to use to run the script, ensuring the shell executes it correctly. Option E is correct because the script file must have execute permission (e.g., set via chmod +x) for the shell to run it directly. Option B is incorrect because comments are allowed and ignored by the shell. Option C is incorrect because the .sh extension is a convention, not a requirement. Option D is incorrect because a script in the current directory can be run with ./script without being in PATH.

Answer

The script must not contain any comments.

Answer

The script must have a .sh extension.

Answer

The script must be in the PATH environment variable.

Question 13

Which THREE of the following commands can be used to transform delimited text (e.g., CSV) by selecting specific fields or columns?

Accepted Answer

cut. Option A, cut, is correct because it is specifically designed to extract selected fields or columns from delimited text, typically using -d to set the delimiter and -f to choose fields (e.g., cut -d, -f1,3 file.csv). Option C, awk, is correct because it can select and transform specific fields using its field separator variable FS and field references like $1, $3, or print statements (e.g., awk -F, '{print $1, $3}' file.csv). Option E, sed, is correct because it can transform delimited text by selecting and manipulating fields through regular expressions and backreferences, for example using sed -E 's/^([^,]*),([^,]*),([^,]*)/\1,\3/' to keep selected columns. Option B, tr, is not correct because it only translates, squeezes, or deletes individual characters and cannot select fields or columns. Option D, cat, is not correct because it merely concatenates and outputs files without any field or column selection capability.

Answer

tr

Answer

cat

Question 14

Refer to the exhibit. What will be the output when this script is executed?

Accepted Answer

a b c
d e f. The script reads two lines from standard input. The first `read a b` reads the first line 'a b c'. Since there are three words but only two variables, the last variable `b` captures the remainder of the line, so a='a' and b='b c'. The second `read d e` reads the second line 'd e f', so d='d' and e='e f'. The `echo -e` command outputs the values with an escaped newline (`
`) between them, producing two lines: 'a b c' and 'd e f', represented as 'a b c
d e f'.

Answer

a b
d e

Answer

a b

Answer

The script will error because of incorrect read syntax.

Question 15

A developer has a directory /home/user/project with many files and subdirectories. They need to change the group ownership of all .txt files to 'developers' and set permissions to 640. Which single command accomplishes this?

Accepted Answer

find /home/user/project -name '*.txt' -exec chown :developers {} \; -exec chmod 640 {} \;. It uses `find` to locate all `.txt` files under `/home/user/project`, then executes `chown :developers` to change the group ownership to 'developers' (the colon before the group name is the correct syntax for setting only the group), followed by `chmod 640` to set the permissions to read/write for the owner and read for the group. Using `-exec` twice in a single `find` command ensures both operations are applied to each matching file without needing a separate command.

Answer

find /home/user/project -name '*.txt' -exec chgrp developers {} \;

Answer

chmod -R 640 /home/user/project/*.txt

Answer

find /home/user/project -name '*.txt' -exec chmod 640 {} \;

Question 16

A log file access.log contains multiple entries per IP address. An administrator wants to display a list of unique IP addresses sorted by frequency (most frequent first). Which command pipeline achieves this?

Accepted Answer

awk '{print $1}' access.log | sort | uniq -c | sort -rn. It extracts the first field (IP address) with awk, sorts them to group identical IPs, counts occurrences with uniq -c, and then sorts numerically in reverse order with sort -rn to display the most frequent IPs first. The -c flag prepends a count to each unique line, and sort -rn sorts by that count descending.

Answer

awk '{print $1}' access.log | sort | uniq | sort -rn

Answer

awk '{print $1}' access.log | sort -rn | uniq -c

Answer

awk '{print $1}' access.log | sort | uniq -c | sort -k2

Question 17

A user frequently runs 'ls -la' and wants to create an alias 'll' for this command. Which command adds this alias persistently?

Accepted Answer

alias ll='ls -la' && echo "alias ll='ls -la'" >> ~/.bashrc. It first creates the alias in the current shell session with the `alias` command, then appends the same alias definition to `~/.bashrc` to make it persistent across new shell sessions. The `&&` ensures the second command runs only if the first succeeds, and `~/.bashrc` is the standard file for user-specific Bash aliases that are sourced on interactive shell startup.

Answer

export ll='ls -la'

Answer

echo "alias ll='ls -la'" >> ~/.bashrc

Answer

alias ll='ls -la'

Question 18

A script running as a daemon should perform clean-up operations when it receives SIGTERM. Which command inside the script sets up this behavior?

Accepted Answer

trap 'cleanup' SIGTERM. The `trap` command in Bash allows a script to catch signals and execute specified commands. The syntax `trap 'cleanup' SIGTERM` registers the `cleanup` function or command to run when the SIGTERM signal (signal 15) is received, which is the standard signal sent by `systemctl stop` or `kill` to request graceful termination of a daemon. This ensures the daemon performs clean-up operations before exiting.

Answer

trap cleanup TERM

Answer

trap 'cleanup' EXIT

Answer

trap "cleanup" 9

Question 19

An administrator needs to find files that have been modified within the last 24 hours. Which two parameters are valid for the find command to accomplish this? (Choose TWO)

Accepted Answer

-mmin 1440. Option A, -mmin 1440, is correct because -mmin takes a number of minutes, and 1440 minutes equals exactly 24 hours, so it matches files whose data was modified within the last 1440 minutes. Option B, -mtime 0, is correct because -mtime counts in 24-hour periods and 0 means less than one full day has elapsed since modification, i.e., within the last 24 hours. Option C, -ctime 0, is wrong because it tests inode status-change time, not file content modification time. Option D, -newer file, is wrong because it compares against another file's timestamp rather than a 24-hour window. Option E, -atime 1, is wrong because it matches access time of exactly one day ago, not modification within the last 24 hours.

Answer

-ctime 0

Answer

-newer file

Answer

-atime 1

Question 20

When writing a Bash script, which two constructs can be used to safely iterate over a list of filenames that may contain spaces or special characters? (Choose TWO)

Accepted Answer

find . -name '*.txt' -exec echo {} \;. Option B is correct because find's -exec action passes each matched pathname directly as an argument to the command without any word splitting or glob expansion, so filenames containing spaces, tabs, or special characters are handled safely (the {} placeholder is replaced with the exact path). Option D is correct because combining read -r with IFS= preserves backslashes and leading/trailing whitespace, and using process substitution with find -print0 (NUL-delimited output) avoids word splitting entirely, making it the canonical safe way to iterate over arbitrary filenames. Option A is unsafe because the unquoted *.txt glob undergoes word splitting on the expanded results, so a filename like 'my file.txt' becomes two iterations. Option C is unsafe because command substitution $(find ...) is subject to word splitting and pathname expansion on its output, breaking on spaces and special characters. Option E is wrong because quoting "*.txt" prevents glob expansion altogether, so the loop iterates once over the literal string *.txt rather than the matching files.

Answer

for file in *.txt; do ... done

Answer

for file in $(find . -name '*.txt'); do ... done

Answer

for file in "*.txt"; do ... done