Count occurrences of character per line/field on Unix

To count occurrence of a character per line you can do:

awk -F'|' 'BEGIN{print "count", "lineNum"}{print gsub(/t/,"") "\t" NR}' file
count lineNum
4       1
3       2
6       3

To count occurrence of a character per field/column you can do:

column 2:

awk -F'|' -v fld=2 'BEGIN{print "count", "lineNum"}{print gsub(/t/,"",$fld) "\t" NR}' file
count lineNum
1       1
0       2
1       3

column 3:

awk -F'|' -v fld=3 'BEGIN{print "count", "lineNum"}{print gsub(/t/,"",$fld) "\t" NR}' file
count lineNum
2       1
1       2
4       3

gsub() function's return value is number of substitution made. So we use that to print the number.
NR holds the line number so we use it to print the line number.
For printing occurrences of particular field, we create a variable fld and put the field number we wish to extract counts from.

grep -n -o "t" stores.dat | sort -n | uniq -c | cut -d : -f 1

gives almost exactly the output you want:

  4 1
  3 2
  6 3

Thanks to @raghav-bhushan for the grep -o hint, what a useful flag. The -n flag includes the line number as well.

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