How to find no of underscores in a variable?

Shell Programming and Scripting
1

Hi
i have a variable var=a_b_c
i want command to find no. of underscores in a variable

Thank you

2

one way:

a=$(echo "$var" | tr -d '[:alpha:]' )
echo ${#a}
3

Hi can you explain the usages of each command that you used.

What tr -d does?
'[:alpha:]'
??

4

another way to do it is by using awk:

echo a_b_c | awk -F_ '{print NF-1}'
5 
tr -d list

Delete the characters found in the list from the input stream.

[:alpha:]

A special character class. In this case instead of listing all the letters from a to z and A to Z use this shorthand. A list of these can be found here

Andrew

6

To count the number of underscores, the most robust solution deletes everything that isn't an underscore.

tr -cd _

Regards,
Alister

7

Using pure Bash (straight, no chaser) :cool::

var="a_b_c"
count="${var//[^_]}"
echo "${#count}"
2
8

The discussion in this thread is a continuation of the discussion in the thread No. of underscores in a file name and was already answered there.