awk

Random numbers generation with awk in BASH shell

If you don’t provide a seed to srand, it will either use the current date and time or a fixed starting seed (this may vary with the implementation). That means, for the former, if your processes run fast enough, they’ll all use the same seed and generate the same sequence. And, for the latter, it … Read more

How to escape a single quote inside awk

This maybe what you’re looking for: awk ‘BEGIN {FS=” “;} {printf “‘\”%s’\” “, $1}’ That is, with ‘\” you close the opening ‘, then print a literal ‘ by escaping it and finally open the ‘ again.

Why does “1” in awk print the current line?

In awk, Since 1 always evaluates to true, it performs default operation {print $0}, hence prints the current line stored in $0 So, awk ‘$2==”no”{$3=”N/A”}1’ file is equivalent to and shorthand of awk ‘$2==”no”{$3=”N/A”} {print $0}’ file Again $0 is default argument to print, so you could also write awk ‘$2==”no”{$3=”N/A”} {print}’ file In-fact you … Read more

Assigning system command’s output to variable

Note: Coprocess is GNU awk specific. Anyway another alternative is using getline cmd = “strip “$1 while ( ( cmd | getline result ) > 0 ) { print result } close(cmd) Calling close(cmd) will prevent awk to throw this error after a number of calls : fatal: cannot open pipe `…’ (Too many open files)

Using AWK to Process Input from Multiple Files

awk ‘FNR==NR{a[$1]=$2 FS $3;next} here we handle the 1st input (file2). say, FS is space, we build an array(a) up, index is column1, value is column2 ” ” column3 the FNR==NR and next means, this part of codes work only for file2. you could man gawk check what are NR and FNR { print $0, … Read more