A user is asking the systems administrator for assistance wi

A user is asking the systems administrator for assistance wi - CompTIA Linux + XK0-005

Question

A user is asking the systems administrator for assistance with writing a script to verify whether a file exists.
Which of the following commands should replace the <CONDITIONAL> string?

Answers

correct

if [ -f "$filename" ]; then
if [ -d "$filename" ]; then
if [ -f "$filename" ] then
if [ -f "$filename" ]; while

Explanation

Correct Answer: A. if [ -f "$filename" ]; then

The correct syntax to check if a file exists in a shell script is if [ -f "$filename" ]; then. The -f flag tests whether the given path refers to a regular file, and the use of brackets and semicolon (;) is required for proper syntax. This structure ensures the script will conditionally execute a block only if the specified file actually exists and is not a directory.

Why other options are incorrect:

B. if [ -d "$filename" ]; then: This checks whether the path is a directory, not a regular file. Since the task is to verify if a file exists, using -d instead of -f makes this condition incorrect for the intended purpose.
C. if [ -f "$filename" ] then: This is a syntax error because it omits the required semicolon (;) or newline before then. Without the proper delimiter, the shell will not parse the statement correctly, resulting in a script error.
D. if [ -f "$filename" ]; while: This is invalid syntax because while cannot follow an if condition like this. The correct control flow keyword following a conditional check should be then, not while. This would cause the shell script to fail.

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