The standard practice for installing software compiled from source is to use the `make install` command (or similar, like `sudo make install`). This leverages the application’s own installation script, which is designed to place binaries, libraries, man pages, and other files into the correct subdirectories under `/usr/local/`. This is more reliable and maintainable than manually copying files, which can miss dependencies or configuration. Symbolic links from system directories or modifying the global PATH for a single application are not standard installation practices.

The `find -mtime n` option works in units of 24-hour periods. `-mtime -7` means “files modified less than 7 * 24-hour periods ago.” A file modified 6 hours ago has not yet completed a full 24-hour period, so from the perspective of `-mtime`, it is 0 periods old. To include it, you would need `-mtime 0`. This is a common point of confusion. While using `-mmin` is a valid workaround, understanding how `-mtime` works is the key practical knowledge being tested.

For security reasons, `sudo` often uses a predefined `secure_path` defined in `/etc/sudoers`. This path is used instead of the invoking user’s `PATH` environment variable. If `/usr/local/bin` is not included in this `secure_path`, commands located there will not be found when run with `sudo`, even if they are in the user’s normal PATH. The correct solution is to modify the `secure_path` directive in `/etc/sudoers` using `visudo` to include the necessary directories.

The `tar` command (Tape ARchive) is the standard tool on Linux for creating a single archive file while preserving Linux file metadata like permissions, ownership, and symlinks. The options `-c` (create), `-z` (compress with gzip), and `-f` (specify filename) create a compressed tarball. While `cp -a` and `rsync` preserve metadata, they create directory copies, not a single file. `zip` is common but does not reliably preserve Linux ownership and some permissions by default.

To interactively explore disk usage and identify the largest consumers, `ncdu` (NCurses Disk Usage) is an excellent tool. As a text-based alternative, the pipeline `du -ah /var | sort -rh | head -20` is a classic and effective method. It gets the disk usage of all items (`-a`) in human-readable format (`-h`) under `/var`, sorts them in reverse human-readable numeric order (`-rh`), and shows the top 20. `ls -laSh` only shows files in a single directory. The `find -exec` command is inefficient for this task. `df` shows filesystem usage, not directory contents.

Both option 2 (shell globbing directly in the for loop) and option 3 (piping `ls` into `while read`) are robust ways to handle filenames with spaces, tabs, or newlines. In option 2, the shell expands the glob `/data/*.txt` into a list, and each filename (even with spaces) is treated as a single item in the `for` loop. In option 3, `read` reads the entire line by default, correctly assigning a filename with spaces to the `file` variable. Option 1, using `$(ls …)`, is the classic pitfall because word splitting occurs on the output of `ls`, breaking filenames with spaces into multiple parts.

When a systemd unit fails, the most direct way to see the error messages from its most recent attempt to start is to query its journal logs. The command `journalctl -u myservice` shows all journal entries for that specific unit. The `-u` flag filters by unit name. `journalctl -xe` shows recent system logs with extended entries, which is more general and might not pinpoint the service’s specific error immediately. Restarting the service without diagnosing the cause will likely just fail again. Checking the service file is useful but won’t show runtime errors.

The correct syntax is `alice ALL=(ALL) /sbin/reboot`. This allows the user ‘alice’ on `ALL` hosts to run the command `/sbin/reboot` as `ALL` users (effectively root). It will prompt for alice’s password. Option 2 adds `NOPASSWD`, which is a specific requirement not mentioned. Option 3 is functionally similar but `(root)` is more restrictive than `(ALL)`. Option 4 restricts it to the hostname ‘localhost’, which is more specific than requested. The core concept tested is the standard sudoers syntax: `user host=(runas) command`.

The crontab format is: `minute hour day month day-of-week`. For 2:15 PM, the hour is 14 in 24-hour format. Weekdays Monday-Friday are represented by days 1-5 (where 0 or 7 is Sunday). Therefore, `15 14 * * 1-5` means “minute 15, hour 14, any day of the month, any month, on days-of-week 1 through 5.” Option 2 uses hour 2 (2 AM). Option 3 uses days 0-4 (Sunday-Thursday). Option 4 uses minute 0 (2:00 PM, not 2:15).

The standard practice for installing software compiled from source is to use the `make install` command (or similar, like `sudo make install`). This leverages the application’s own installation script, which is designed to place binaries, libraries, man pages, and other files into the correct subdirectories under `/usr/local/`. This is more reliable and maintainable than manually copying files, which can miss dependencies or configuration. Symbolic links from system directories or modifying the global PATH for a single application are not standard installation practices.0