The first 512-byte sector of a bootable disk is the Master Boot Record (MBR). Its primary limitation is the use of 32-bit values for sector addresses, which limits the addressable disk space to 2^32 sectors. With a standard sector size of 512 bytes, this equates to a maximum of 2 TB (or 2.2 TB when calculated as 2^32 * 512 bytes). This limitation was a key driver for bootloaders that could understand more modern partitioning schemes like GPT.

The ‘ldd’ command lists the shared libraries required by a binary. If a required library is missing, corrupted, or has incorrect permissions, the binary will fail to execute, often with a vague ‘command not found’ or similar error. Running ‘ldd /bin/ls’ will quickly show if all dependencies are resolvable, making it the most efficient first diagnostic step for this specific symptom.

The ‘set -e’ option (or ‘set -o errexit’) causes a shell script to exit immediately if any command it executes returns a non-zero exit status (indicating failure). This is the standard and most direct way to achieve the described behavior. While ‘trap’ can be configured to catch errors, ‘set -e’ is simpler for this specific requirement. ‘set -o pipefail’ is related but deals with pipelines, and ‘exec 2>&1’ redirects stderr to stdout.

The ‘-mmin’ test checks for modification time in minutes. 48 hours equals 2880 minutes, so ‘-mmin -2880’ finds files modified less than 2880 minutes ago. ‘-mtime -2’ finds files modified less than 2*24=48 hours ago, but its granularity is in days, not hours, so it might miss files modified just over 24 hours ago. ‘-ctime’ checks inode change time (metadata), and ‘-atime’ checks access time, neither of which reliably indicates content modification.

The pipeline ‘grep ERROR data.txt | grep -v TESTING’ first selects all lines containing ‘ERROR’, then passes that result to a second grep which filters out (-v) any lines containing ‘TESTING’. This is a standard and effective pattern for compound conditions. Option B would incorrectly exclude lines containing the sequence ‘ERROR…TESTING’ anywhere, not lines containing ‘TESTING’ at all. Option C is invalid syntax, and Option D uses a non-existent grep flag.

By default, on Debian and Ubuntu, ‘apt-get install’ does NOT install ‘Recommends’ packages. To install a package along with its recommended packages, you must explicitly use the ‘–install-recommends’ flag. The default command (option A) would not install recommends. Option C’s ‘–no-install-suggests’ is the default behavior for ‘Suggests’. Option D is not a valid apt-get flag.

In the standard crontab format, the day of week field (the 5th field) can use numbers 0-7, where both 0 and 7 represent Sunday. Therefore, 1=Monday, 2=Tuesday, 3=Wednesday, 4=Thursday, 5=Friday, 6=Saturday. The range ‘1-5′ correctly represents Monday through Friday. The original statement in the question is a trick; the developer’s entry is actually correct. The time fields ’15 2’ (minute hour) are in the correct order. The absolute path is good, and the asterisks are the proper wildcards.

USB storage devices, like SATA and SCSI disks, use the ‘sd’ (SCSI disk) driver. The letters are assigned sequentially: sda, sdb, sdc, etc. Partitions are numbered starting from 1. Therefore, the third disk would be ‘sdc’, and its first partition would be ‘sdc1’. /dev/hd* is for older IDE/PATA drives. While /dev/disk/by-uuid/ contains symlinks, the question asks for the primary device file node.

In vi’s command mode, the forward search command is initiated by pressing the ‘/’ key, followed by the search pattern (‘config’), and then terminated by pressing the Enter key. The ‘?’ key initiates a reverse search. ‘:s’ is the substitution command, and ‘f’ is the command to find a character on the current line.

The first 512-byte sector of a bootable disk is the Master Boot Record (MBR). Its primary limitation is the use of 32-bit values for sector addresses, which limits the addressable disk space to 2^32 sectors. With a standard sector size of 512 bytes, this equates to a maximum of 2 TB (or 2.2 TB when calculated as 2^32 * 512 bytes). This limitation was a key driver for bootloaders that could understand more modern partitioning schemes like GPT.0