Word Count using AWK - awk

Question

I have file like below :
this is a sample file
this file will be used for testing
this is a sample file
this file will be used for testing
I want to count the words using AWK.
the expected output is
this 2
is 1
a 1
sample 1
file 2
will 1
be 1
used 1
for 1
the below AWK I have written but getting some errors
cat anyfile.txt|awk -F" "'{for(i=1;i<=NF;i++) a[$i]++} END {for(k in a) print k,a[k]}'

Answer 1

It works fine for me:
awk '{for(i=1;i<=NF;i++) a[$i]++} END {for(k in a) print k,a[k]}' testfile
used 1
this 2
be 1
a 1
for 1
testing 1
file 2
will 1
sample 1
is 1
PS you do not need to set -F" ", since its default any blank.
PS2, do not use cat with programs that can read data itself, like awk
You can add sort behind code to sort it.
awk '{for(i=1;i<=NF;i++) a[$i]++} END {for(k in a) print k,a[k]}' testfile | sort -k 2 -n
a 1
be 1
for 1
is 1
sample 1
testing 1
used 1
will 1
file 2
this 2

Answer 2

Instead of looping each line and saving the word in array ({for(i=1;i<=NF;i++) a[$i]++}) use gawk with multi-char RS (Record Separator) definition support option and save each field in array as following(It's a little bit fast):
gawk '{a[$0]++} END{for (k in a) print k,a[k]}' RS='[[:space:]]+' file
Output:
used 1
this 2
be 1
a 1
for 1
testing 1
file 2
will 1
sample 1
is 1
In above gawk command I defines space-character-class [[:space:]]+ (including one or more spaces or \new line character) as record separator.

Answer 3

Here is Perl code which provides similar sorted output to Jotne's awk solution:
perl -ne 'for (split /\s+/, $_){ $w{$_}++ }; END{ for $key (sort keys %w) { print "$key $w{$key}\n"}}' testfile
$_ is the current line, which is split based on whitespace /\s+/
Each word is then put into $_
The %w hash stores the number of occurrences of each word
After the entire file is processed, the END{} block is run
The keys of the %w hash are sorted alphabetically
Each word $key and number of occurrences $w{$key} is printed