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How to find no of underscores in a variable?

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# 1  
Old 09-13-2013
How to find no of underscores in a variable?
Hi
i have a variable var=a_b_c
i want command to find no. of underscores in a variable

Thank you
# 2  
Old 09-13-2013
one way:
Code:
a=$(echo "$var" | tr -d '[:alpha:]' )
echo ${#a}

# 3  
Old 09-13-2013
Quote:
Originally Posted by jim mcnamara
one way:
Code:
a=$(echo "$var" | tr -d '[:alpha:]' )
echo ${#a}


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

What tr -d does?
'[:alpha:]'
??
# 4  
Old 09-13-2013
another way to do it is by using awk:
Code:

echo a_b_c | awk -F_ '{print NF-1}'

# 5  
Old 09-13-2013
Quote:
Originally Posted by targetshell
Hi can you explain the usages of each command that you used.

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

Delete the characters found in the list from the input stream.
Code:
[: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  
Old 09-13-2013
Quote:
Originally Posted by jim mcnamara
Code:
tr -d '[:alpha:]'

To count the number of underscores, the most robust solution deletes everything that isn't an underscore.
Code:
tr -cd _

Regards,
Alister
# 7  
Old 09-13-2013
Using pure Bash (straight, no chaser) Smilie:

Code:
var="a_b_c"
count="${var//[^_]}"
echo "${#count}"
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