UNIX/Linux Command Line and System Administration

MBR (Master Boot Record) partitioning scheme allows a maximum of 4 primary partitions. This is a fundamental limitation of the MBR partition table structure. Extended partitions can be created to work around this, but strictly speaking, only 4 primary partitions are allowed in MBR.

GPT (GUID Partition Table) allows a maximum of 128 partitions, which is a significant advantage over MBR's 4-partition limit. GPT uses 64-bit partition entries, supporting virtually unlimited partitions for practical purposes, though the standard specifies 128 as the typical maximum. Options A (24), B (64), C (12), and D (4) are incorrect.

Bootstrap and bootloader are NOT the same thing and are NOT at the same location. The bootstrap is the initial firmware code (in ROM/EEPROM) that starts the boot process, while the bootloader (like GRUB or Windows Boot Manager) is software on disk that loads the OS. They reside in different memory locations and serve different stages of the boot process.

Common hard drive interfaces include SATA (Serial ATA) and PATA (Parallel ATA) for internal drives. FireWire and iLink (IEEE 1394) are external interfaces used with external hard drives. PRIMARY is not an interface type - it refers to a primary partition. NT is not a valid hard disk interface.

The standard kill command sends SIGTERM (15), which allows the process to catch the signal, clean up, and terminate gracefully. Kill -9 sends SIGKILL (9), which cannot be caught or ignored - the kernel terminates the process immediately without any cleanup opportunity. Child processes are not automatically handled by SIGKILL.

The crontab -r command removes the current user's crontab file completely. In contrast, crontab -l lists the crontab contents, crontab -e opens it for editing, and crontab -t is not a valid crontab option.

chmod 644 sets permissions as: owner gets read (4) + write (2) = 6, group gets read (4) = 4, others get read (4) = 4. This results in read/write for owner and read-only for everyone else. Execute permission would require adding 1 to the octal value.

The standard syntax to connect to a remote host as a specific user is ssh user@hostname. Although ssh hostname is valid because it defaults to the current local user, the specified option is the most complete way to define user-specific authentication.

The crontab format is: minute hour day-of-month month day-of-week command. In '0 12 14 2 ', the fields are: minute=0, hour=12, day-of-month=14, month=2, day-of-week=. The 14 specifies day of month, which is not listed in options A-C. Option D is correct.

The gunzip command is used to decompress gzip files. Applying the -f or --force option forces decompression and overwrites any existing uncompressed files with the same name without prompting, whereas the other options incorrectly suggest that this command performs file compression.

The command 'rm -r *' recursively removes all files and subdirectories from the current directory. The -r flag enables recursive deletion. 'rm -rf' would also work but requires a directory name argument. 'rm

A symbolic (soft) link has its own inode and permissions separate from the target file. The link's permissions are independent of the original file's permissions. This is different from a hard link, which shares the same inode and thus the same permissions as the original file.

To execute a file in Unix, use './' which tells the shell to look for the file in the current directory. The '.' represents the current directory. '. filename' sources the file (runs it in the current shell context), '/ filename' is invalid syntax, and '. <filename>' is also incorrect.

The correct command is 'fg' (foreground), which by default operates on job specifications, not PIDs. To move a background job to foreground, use 'fg' or 'fg %jobnum'. Using 'fg pid' is technically incorrect syntax - fg expects a job ID (like %1), not a process ID. However, option A is intended as the correct answer among the choices.

All three commands can be used to identify the logged-in user: 'who' lists all logged-in users, 'who am I' shows the current user's terminal session info, and 'id' displays detailed user and group information. The question asks which combination can be used, and all three are valid for finding user information.

The find command with '/' searches from root, '-name' with wildcards matches patterns, and '$1>list' (should be '2>list') redirects stderr to suppress errors. Options B and D lack wildcards for partial matching, and option C searches only current directory. However, the correct syntax is '2>' not '$1>' for stderr redirection.

The 'tr' command translates characters. Using 'cat test1 | tr ' ' '|' > test2' reads the file, translates all spaces to pipe characters, and redirects output to test2. Option B uses 'cut' incorrectly for this purpose, option C translates pipes to spaces (reverse of what's asked), and option D doesn't perform any transformation.

The 'tr -s' option squeezes repeated characters, so 'tr -s ' '' squeezes multiple consecutive spaces into single spaces. The cut command is for field extraction, not character suppression. Option B correctly uses tr with -s flag to compress multiple spaces into one.

The cut command extracts specific columns from delimited text. With space delimiter (-d ' '), -f2 extracts the second field. Option A extracts field 1, and C uses default tab delimiter. The correct command to get the second column is cut -d ' ' -f2.

VI/VIM loads the entire file into memory for editing. When viewing large log files, this can consume significant RAM and become slow. Tools like less, more, or tail are preferred for log viewing as they don't require loading the entire file.