Basic Unix Quiz - 4

The answer is C, -i.

The -i option tells the rm command to prompt the user before deleting each file. This is useful if you want to make sure you are deleting the correct files.

The other options are not correct.

• -r recursively deletes directories and their contents.
• -x forces the rm command to continue even if it encounters errors.
• -1 prompts the user once before deleting more than three files.

Here is an example of how to use the -i option:

rm -i file1 file2 file3

This will prompt the user to confirm the deletion of each file. For example, the user might be prompted with the following:

rm: remove file1? (y/N)

If the user enters y, the file will be deleted. If the user enters N, the file will not be deleted.

The ls -t command sorts files by modification time, showing the most recently modified files first. This is the standard option for listing files chronologically by when they were last changed.

In vi/vim editors, the % key moves the cursor between matching delimiters - pressing % on a parenthesis, bracket, or brace will jump to its closing or opening counterpart. This is useful for navigating code and structured text.

The ps (process status) command displays information about active processes, including their process IDs, resource usage, and execution status. It is the standard Unix/Linux tool for viewing process characteristics.

The 'file' command in Unix/Linux examines the contents of a file and performs several tests (including magic number checks) to determine its file type (e.g., ASCII text, executable, PDF). 'ls' lists files, 'cat' displays content, and 'more' is a pager.

The cut command uses the -d option to specify the delimiter (field separator). For example, cut -d: uses : as the delimiter to split input into fields. This is the standard way to define what character separates fields when extracting columns.

The -d option displays the number of blocks used by a file, showing disk usage in block units rather than the default byte count. This is useful when you need to see file size in filesystem blocks.

The touch command with -a option changes only the access time (atime) of a file to the current time. By default, touch updates both access and modification times, but -a restricts it to just the access timestamp.

chmod -R a+x progs recursively makes all files and subdirectories in the 'progs' directory executable for all users. The -R flag applies permissions recursively, 'a' means all users, and '+x' adds execute permission.