Basic Unix Quiz - 2

The wildcard * matches any string (including empty). cat ch matches 'patch' (ch at end), 'catch' (ch at start), and '.ch' (ch at start). Since all options match, 'All of the above' is correct.

In octal notation, 7 (binary 111) represents read, write, and execute permissions, while 5 (binary 101) represents read and execute. Therefore, 755 grants the owner full permissions and gives the group and others only read and execute permissions. 744 would leave group/others without execute permission.

The stty command changes terminal settings. 'stty intr ^c' sets the interrupt character to Control-c. Option B uses 'stty intr ^c' (escaping the caret) which achieves the same result in a shell context. Option A uses 'tty' which prints terminal info, and 'echoe' controls erasure.

grep is a text search utility, not a communication command. write, mesg, and mail are all UNIX commands for user-to-user communication.

In vi editor, the } key moves the cursor forward to the end of the current paragraph. { moves to beginning of paragraph, | moves to specific column, $ moves to end of line.

The wildcard [!0-9] matches any single character that is not a digit. Combined with emp, it targets files starting with 'emp' followed by a non-numeric character. Option 304 uses more and incorrect brackets, while 305 and 306 are too restrictive, only matching specific lowercase letter ranges.

The 'tee' command reads from standard input and writes to both standard output and one or more files simultaneously. It is commonly used in shell pipelines to 'split' the data stream, allowing you to view progress while saving the results to a file.

rm (remove) is the standard UNIX command to delete files. mv moves or renames files, remove is not a valid command, and del is not standard UNIX (it's a DOS command).

The semicolon (;) is used to separate multiple commands on a single line in UNIX shells, allowing sequential execution. $ is for variables, # for comments, : has other uses.