Here are some awk examples to sum an integer column from a file or stdin (standard input) stream.
Data used in these examples
1 2 badval 4
Awk sum example on command line
Lines with invalid numbers are treated as 0. To sum values from stdin use the following command:
cat data1.txt | awk '{ S+=$1} END {print S}'
7
Env: GNU bash, version 4.2.46
To sum values from file use the following command:
awk '{ S+=$1} END {print S}' data1.txt
7
Env: GNU bash, version 4.2.46
Bash alias for awk sum code
Put the following line in your ~/.bash_profile
alias mysum="awk '{ S+=\$1} END {print S}'"
When you login next time, you can simply run
$ mysum data1.txt ##or $ cat data1.txt | mysum