Keep Filenames in One Argument

Let's say the teacher named a report class marks.txt. That space is perfectly acceptable in a filename, but it needs care in a command. The shell does not automatically know that two unquoted words are one name. Before a utility receives the line, the shell processes the text and decides which arguments to pass.

An argument is one item supplied to a command: perhaps an option or a filename. Quotes help you keep a value together as one argument. When a variable holds a path, double-quoting its expansion is usually the straightforward choice. You get the stored value without inviting the shell to split it into words or expand wildcard characters in it.

Prepare the example

Use a new practice folder. We will store a filename in a variable called report, write a mark to that file, then read it back. You do not type a dollar sign when assigning the variable. You use the dollar sign later when asking for its stored value.

Bash · Linux terminal

report='class marks.txt'
printf 'Diya: 72\n' > "$report"
cat "$report"

Expected result

Diya: 72

In report='class marks.txt', the single quotes preserve the filename text during assignment. The expression "$report" is different: double quotes allow the variable to expand while keeping the resulting name together. The redirection therefore writes to one file with a space in its name.

The final cat receives that same single filename. If you removed the double quotes around its expansion, the shell could split the value into class and marks.txt. If you used single quotes around $report, it would pass the literal characters $report instead of the stored name. Both mistakes happen before cat can do the job you intended.

Your task: Keep the filename stored in report as one argument.

Use a new practice folder. We will store a filename in a variable called report, write a mark to that file, then read it back. You do not type a dollar sign when assigning the variable. You use the dollar sign later when asking for its stored value.

Bash · complete example for this question

report='class marks.txt'
printf 'Diya: 72\n' > "$report"
cat "$report"

Expected result

Diya: 72

Worked answer

cat "$report"

Choose cat "$report". You want two things at once: expand the variable and preserve its value as one argument. Double quotes do both here. After running the command, a file listing should show one report name containing a space, not two files named after its separate words.

Quote according to what should reach the command. Single quotes preserve literal text; double quotes still permit variable expansion while keeping the expanded value together. When a path comes from a variable, get into the habit of quoting that expansion rather than relying on every future filename to contain no spaces.