The result of "ls | wc -l" does not match the real number of files

Question

I need to count the number of files under a folder and use the following command.

cd testfolder
bash-4.1$ ls | wc -l
6

In fact, there are only five files under this folder,

bash-4.1$ ls
total 44
-rw-r--r-- 1 comp 11595 Sep  4 22:51 30.xls.txt
-rw-r--r-- 1 comp 14492 Sep  4 22:51 A.pdf.txt
-rw-r--r-- 1 comp  8160 Sep  4 22:51 comparison.docx.txt
-rw-r--r-- 1 comp   903 Sep  4 22:51 Survey.pdf.txt
-rw-r--r-- 1 comp  1206 Sep  4 22:51 Steam Table.xls.txt

It looks like ls | wc -l even counts the total 44 as a file, which is not correct.

wc -l is working as it should. Please run the command type ls and report what you see. — John1024, Sep 05 '16 at 04:11
It returns 6 because wc -l counts the number of lines... it's including the line that says total 44. — cutrightjm, Sep 05 '16 at 04:23
see also: http://unix.stackexchange.com/questions/1125/how-can-i-get-a-count-of-files-in-a-directory-using-the-command-line — Sundeep, Sep 05 '16 at 04:43

score 12 · Answer 1 · answered Sep 05 '16 at 06:32

12

Just a extra info for the above,

You should use find instead of ls if you like to process the output, it has some futures which are more suitable (e.g. -print0) for piping the result to other applications.

In the above case you can use it like this,

find . -type f | wc -l

which will list any files on the current directory.

answered Sep 05 '16 at 06:32

Rabin

3,883
1
22
23

1

why not use -exec instead of piping the result... – Sundeep Sep 05 '16 at 06:47
3

@spasic because that would count the lines inside each file instead of number of files – Random832 Sep 05 '16 at 09:32
oops, good point :).. searching for find + wc gave this good Q&A - http://stackoverflow.com/questions/1412244/use-find-wc-and-sed-to-count-lines – Sundeep Sep 05 '16 at 09:38
1

Will break if filename contains newline. – 123 Sep 05 '16 at 14:22
1

@123, in this uniq case you can use find . -type f -print0 | wc --files0-from=- which use null as the delimiter. – Rabin Sep 05 '16 at 22:04

score 10 · Answer 2 · edited Sep 05 '16 at 07:15

10

It's not working because wc -l returns the number of lines of the output of the ls command, which in this case includes total 44. Since your shell has an alias for ls as ls -cml, you're getting that extra information which is messing up your output.

Instead, use the command "ls" -Aq | wc -l. The -A command lists all files in the directory including dotfiles, but excludes . and ... The quotations here are important - they ignore the alias and run /bin/ls directly.

-q makes sure that file names are all printed on one line only even if they contain newline characters (which would then be rendered as ?).

edited Sep 05 '16 at 07:15

Stéphane Chazelas

544,893

answered Sep 05 '16 at 04:27

cutrightjm

5,290

1

Note that "ls" won't help if ls is defined as a function instead of an alias (or if there's also an alias for "ls" though that's less likely and not even supported by some shell). command ls may be more foolproof. – Stéphane Chazelas Sep 05 '16 at 07:10
Hmm... on bash: alias command="echo foo", command ls, outputs foo ls. Wonderful. At least it doesn't accept /bin/ls as an alias name. – ilkkachu Sep 05 '16 at 07:48
I find "ls" a bit unclear. /bin/ls explicitly conveys what you are doing. – Martin Nyolt Sep 05 '16 at 08:55
@ikkachu, the idea is that it's common to have a function for ls (like ls() { [ ! -t 1 ] || set -- -F "$@"; command ls "$@"; }), while it's uncommon for command to be an alias (except on AT&T ksh where command is a builtin alias) – Stéphane Chazelas Sep 05 '16 at 10:01
you can also say env ls. env doesn't know about your shell aliases, functions etc., and if you call it like that it's a no-op. – badp Sep 05 '16 at 21:50

score 8 · Accepted Answer · answered Sep 05 '16 at 04:08

8

wc is a char, word, and line counter, not a file counter.

You, the programmer/script writer, are responsible for making it count what you want and to adjust the calculation accordingly.

In your case, you could do something like:

echo $((`ls|wc -l`-1))

Finally note that your ls is probably an alias as it gives a long listing which is not the normal ls without arguments. It may therefore be a good idea to refer to ls's full path (usually /bin/ls) to avoid confusion.

answered Sep 05 '16 at 04:08

Julie Pelletier

7,622

1

If I use /bin/ls | wc -l it will count 5 instead of 6 – user288609 Sep 05 '16 at 04:17
Also, echo $((ls|wc -l-1)) also give the correct count. Would you like to explain what does your command really do? – user288609 Sep 05 '16 at 04:19
Of course. I showed you 2 solutions to show you how you can deal with calculations in bash. – Julie Pelletier Sep 05 '16 at 04:19
It subtracts 1 from the result of wc on your aliased ls. – Julie Pelletier Sep 05 '16 at 04:21
2

If you put it in a script, it probably won't have the alias and as I mentioned it would be a better idea to use /bin/ls|wc -l. – Julie Pelletier Sep 05 '16 at 04:22

heemayl · Answer 4 · 2016-09-05T20:27:16.190

As others have already mentioned, doing ls | wc -l is not always a reliable way to get files count in a directory.

Here are some reliable ways:

You can get find to print a . for each file found and get wc -l to count the number of lines:
```
 find . -type f -printf '.\n' | wc -l
```
If there are not many files in the directory, you can save the file names in an array and then get the length of the array:
```
 for f in *; do [ -f "$f" ] && files+=("$f"); done && echo "${#files[@]}"
```
For all files and directories, this gets easier:
```
 files=( * ) && echo "${#files[@]}"
```

Example:

$ touch $'foo\nbar' 'foo bar' spam                         

$ ls | wc -l                      
4

$ find . -type f | wc -l                                   
4

$ find . -type f -printf '.\n' | wc -l
3

$ for f in *; do [ -f "$f" ] && files+=("$f"); done

$ echo "${#files[@]}"
3

@roaima you know what you just made me feel like a stupid now, i don't know what i was thinking then. — heemayl, Sep 05 '16 at 20:21
@roaima I have made an edit. All credit goes to you. Thanks. — heemayl, Sep 05 '16 at 20:27

score 0 · Answer 5 · answered Sep 05 '16 at 14:29

bash-4.1$ ls
1. total 44
2. -rw-r--r-- 1 comp 11595 Sep  4 22:51 30.xls.txt
3. -rw-r--r-- 1 comp 14492 Sep  4 22:51 A.pdf.txt
4. -rw-r--r-- 1 comp  8160 Sep  4 22:51 comparison.docx.txt
5. -rw-r--r-- 1 comp   903 Sep  4 22:51 Survey.pdf.txt
6. -rw-r--r-- 1 comp  1206 Sep  4 22:51 Steam Table.xls.txt

That's correct, there are 6 lines in the output. You might want to use: ls -1 which corresponds to single column format and it looks like this:

ls -1
Desktop
Documents
Downloads
Music
Pictures
Public
Templates
Videos

Now wc -l returns correct number of files:

ls -1 | wc -l
8

If you try ls | cat you'll see that ls automatically switches to ls -1 format when talking to something that isn't a terminal. Unless it's been overridden with an alias that stops it doing so. (Which is what was happening to the OP.) — Chris Davies, Sep 05 '16 at 15:09

The result of "ls | wc -l" does not match the real number of files

5 Answers5