awk - Collapse sequential numbers to ranges in bash -

awk - Collapse sequential numbers to ranges in bash -

i trying collapse sequential numbers ranges in bash. example, if input file

1 2 3 4 15 16 17 18 22 23 45 46 47

i want output as:

1 4 15 18 22 23 45 47

how can awk or sed in single line command?

thanks help!

$ awk 'nr==1{first=$1;last=$1;next} $1 == last+1 {last=$1;next} {print first,last;first=$1;last=first} end{print first,last}' file 1 4 15 18 22 23 45 47

explanation

nr==1{first=$1;last=$1;next}

on first line, initialize variables first , last , skip next line.

$1 == last+1 {last=$1;next}

if line continues in sequence last, update last , jump next line.

print first,last;first=$1;last=first

if here, have break in sequence. print out range lastly sequence , reinitialize variables new sequence.

end{print first,last}

after end of file, print final sequence.

bash awk sed collapse