Unix/Linux Command Line Operations

chmod (option A) is the standard Unix/Linux command to change file access permissions (read, write, execute). chroot (B) changes the root directory, chaccess (C) doesn't exist, and chgrp (D) changes group ownership, not permissions.

dig (option C, Domain Information Groper) is a flexible DNS lookup tool. nslookup (A) is older but also works for DNS queries. dnslookup (B) and lookup (D) are not standard DNS commands. While nslookup is also valid, the question specifically asks for the command used, and dig is the preferred modern tool.

fuser (option B) identifies and can kill processes accessing a specified file. kill (A) terminates processes by PID but doesn't find them by file. proc (C) and killproc (D) are not standard commands. fuser is specifically designed to find processes using files.

The head command outputs the first part (default first 10 lines) of one or more files. top displays running processes, start is not a standard Unix command for this purpose, and first does not exist as a file viewing command.

ifconfig (interface config) is the standard Unix/Linux command to configure or display network interface parameters. ipconfig is the Windows equivalent, nslookup queries DNS records, and ethconfig is not a valid command.

netstat (network statistics) displays network connections, routing tables, interface statistics, and masquerade connections. ifconfig/all is not a valid command syntax, ipconfig/all is Windows-specific, and nslookup only queries DNS.

tracert (trace route) is the Windows command that traces the path packets take to a destination host, showing each hop. findhost, tracerout (misspelled), and rootfind are not valid network diagnostic commands.

The whoami command prints the effective username of the current user, matching the behavior of id -un. In contrast, who displays a list of all currently logged-in users, while whologgedin and user are not standard Unix commands for retrieving the current active user.

vmstat (virtual memory statistics) reports system virtual memory, processes, paging, block IO, traps, and CPU activity. stats, virstat, and vmdetail are not standard Unix commands.

In Unix/Linux, combining the -i option (which prints the index number or inode of each file) with the -l option (which prints the long listing format) results in the command ls -li. Other options like ls -ll or ll do not print the inode numbers.

In Unix/Linux, filenames starting with a dash are interpreted as command options. Using './-sag' provides a path prefix, preventing the dash from being treated as an option flag. The 'rm -f' and 'rm -m' flags are incorrect approaches.

The tree command in Unix/Linux displays the directory structure in a hierarchical tree format, showing files and subdirectories. It does not show process information (that would be ps) and basic tree does not include timestamps by default.

To run ipconfig on Windows, you must open the command line prompt. Running CMD in the Start menu Run dialog opens the command prompt window, allowing the execution of ipconfig. Typing CONFIG or RUN inside the run box will not launch the command shell.