Question:

How do I know the space s in a file are white spaces or tabs in UNIX?

Answer:

Method 1:

Use vi or vim,

After opening the file, type :set list, all the tabs will shown as “^I”

$ vi abc

This file^Icontains some spacesĀ  and^I^Itabs.$
Do you^I see any ^I ^I tab?$
~

Method 2:

Use cat command with -vt flags.

$ cat -vt abc

This file^Icontains some spacesĀ  and^I^Itabs.
Do you^I see any ^I ^I tab?