sh – I want to calculate how many ascii characters given by a variable are in the standard input

Question: Question:

In a shell script, I want to calculate how many ASCII characters are specified by the variable sep from standard input. How can this be achieved?

Answer: Answer:

od | sort | uniq -c script to create and search histograms:

#!/bin/sh
sep="$1"
pat="($(set -- $(printf %s "$sep" | od -v -An -tx1) && IFS=\| && echo "$*"))\$"
od -v -An -tx1 | xargs -n1 | sort | uniq -c | grep -E "$pat"

Execution example:

$ echo -e " AB...CD\n abcd " | ./script.sh "aB.C 
"
      2 0a
      3 20
      3 2e
      1 42
      1 43
      1 61

If you can use od -w1 , you can make the output a little more straightforward (albeit subtle) by doing the following:

od -v -An -tax1 -w1 | xargs -n2 | sort -k2 | uniq -c | grep -E "$pat"

Execution example:

$ echo -e " AB...CD\n abcd " | ./a.sh "aB.C 
"
      2 nl 0a
      3 sp 20
      3 . 2e
      1 B 42
      1 C 43
      1 a 61