how to write finding output to same file using awk command

Question

awk \'/^nameserver/ && !modif { printf(\"nameserver 127.0.0.1\\n\"); modif=1 } {print}\' testfile.txt

It is displaying output but I want to wri

Answer 1

Despite the fact that using a temp file is correct, I don't like it because :

• you have to be sure not to erase another temp file (yes you can use mktemp - it's a pretty usefull tool)

• you have to take care of deleting it (or moving it like thiton said) INCLUDING when your script crash or stop before the end (so deleting temp files at the end of the script is not that wise)

• it generate IO on disk (ok not that much but we can make it lighter)

So my method to avoid temp file is simple:

my_output="$(awk '(PROGRAM)' source_file)"
echo "$my_output" > source_file

Note the use of double quotes either when grabbing the output from the awk command AND when using echo (if you don't, you won't have newlines).