Find count of files matching a pattern in a directory in linux

Question

I am new to linux. I have a directory in linux with approx 250,000 files I need to find count of number of files matching a pattern.

I tried using following command :

ls -1 20061101-20131101_kh5x7tte9n_2010_* | wc -l 

I got the following error message:

-bash: /bin/ls: Argument list too long 0 

Please help. Thanks in advance

Answer 1

It might be better to use find for this:

find . -name "pattern_*" -printf '.' | wc -m 

In your specific case:

find . -maxdepth 1 -name "20061101-20131101_kh5x7tte9n_2010_*" -printf '.' | wc -m 

find will return a list of files matching the criteria. -maxdepth 1 will make the search to be done just in the path, no subdirectories (thanks Petesh!). -printf '.' will print a dot for every match, so that names with new lines won't make wc -m break.

Then wc -m will indicate the number of characters which will match the number of files.

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Performance comparation of two possible options:

Let's create 10 000 files with this pattern:

$ for i in {1..10000}; do touch 20061101-20131101_kh5x7tte9n_201_$i; done 

And then compare the time it takes to get the result with ls -1 ... or find ...:

$ time find . -maxdepth 1 -name "20061101-20131101_kh5x7tte9n_201_*" | wc -m 10000  real    0m0.034s user    0m0.017s sys     0m0.021s  $ time ls -1 | grep 20061101-20131101_kh5x7tte9n_201 | wc -m 10000  real    0m0.254s user    0m0.245s sys     0m0.020s 

find is x5 times faster! But if we use ls -1f (thanks Petesh again!), then ls is even faster than find:

$ time ls -1f | grep 20061101-20131101_kh5x7tte9n_201 | wc -m 10000  real    0m0.023s user    0m0.020s sys     0m0.012s