How does wc -l `ls` give the actual number of lines?

Question

Can anyone explain to me how does this command work.

wc -l `ls`

while this command gives the total number of java lines or txt lines.

Answer 1

ls outputs a list of file/directory names in the current directory.

`ls` will be replaced by the output of ls. So you're actually running something like:

wc -l file1 file2 file3 ... fileN

And of course wc will open each file named in the command line in turn, to count the lines.

The same effect could be had by running:

wc -l *

Note that this only holds if none of the file names in the current directory contain any “weird” character (whitespace or \[?*).