- 1 year ago
What's wrong with repeating entries in awk print statements?
In awk
, repeating entries in print statements can occur due to the unintended use of multiple expressions separated by commas within the print
statement. This behavior is not specific to awk
but rather a result of how the comma operator works in many programming languages, including awk
.
When you use a comma operator in awk
or other languages, each expression separated by a comma is evaluated independently, and the result of the last expression is used as the value of the comma operator. As a result, if you have repeating entries separated by commas in a print statement, the output will reflect the value of the last expression only.
Consider the following awk
code snippet as an example:
awkawk '{ print $1, $2, $1 }' input.txt
Assuming input.txt
contains three columns of data, the intention here might be to print the first column, the second column, and then repeat the first column. However, due to the use of commas, only the value of the last expression ($1
) will be printed, resulting in a repetition of the first column.
To achieve the desired output, you can concatenate the values using the concatenation operator (""
). Here's the modified code:
awkawk '{ print $1, $2, $1""$2 }' input.txt
By using the concatenation operator (""
), the values of $1
and $2
are combined, resulting in the desired output where the first column and second column are printed separately, and then the first column is concatenated with the second column.