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How to sum a particular column of a CSV file with awk
Answer:
Assume you have a CSV file like the following (only contain number)
1,2,3 2,3,4 3,4,5 ...
How do you sum the nth column of this file? It is easy with the use of awk
e.g. Assume you want to sum the 2nd column:
# awk -F "," '{ sum += $2 } END { print sum }' test.txt
Multiple separators in awk
Answer:
Sometimes when you split a string using awk, you need to support more than 1 separators, you can use the -F option.
E.g.
# cat foo.txt | awk -F "[ ?]" '{print $7}'
Now the awk split by a space and by a ?.
Extract column data using awk
Answer:
A simple awk command print the 1st column of top command
# top -bc -n1 | awk '{print $1}'
If you want to specify the field separator, you can do the following
# awk -F':' '{print $1}' /etc/passwdWhich print the 1st column of file /etc/password, as if they are split by :
How to remove BOM from UTF-8?
Answer:
# awk '{if(NR==1)sub(/^\xef\xbb\xbf/,"");print}' text.txt
Source: http://stackoverflow.com/questions/1068650/using-awk-to-remove-the-byte-order-mark
Updated: (Suggested by Van Overveldt Peter)
# tail --bytes=+4 text.txt
Remove empty lines in a file
Answer
Pick any one of the following methods.
1. grep
grep . test.txt
2. sed
sed '/^$/d' test.txt
3. awk
awk NF test.txt
4. tr
cat test.txt | tr -s "\n"
5. perl
perl -n -e 'print unless /^$/' test.txt
