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I am trying to devise a solution to rename a large collection of files so that the text in line 3 of each file is the new filename. These files all have the same structure. My scripting ability is poor so I am hoping this problem has been approached before by others so I don't need to invent a new wheel? I've been consulting some sed and awk tutorials but not finding a solution there.

These are HTML files and specifically line 3 of each file looks like this.

<TITLE>DATA POPULATION 'CODE on group 1234 by THING'</TITLE>

I want to grab everything between the single quotes and use that text to rename the file with that text as the filename.

Can anyone point me down the right path to approach this task? The notion of renaming these one at a time would just be murder.

Thanks for reading and pondering this problem.

$ awk -v FS="'" -v OFS="t" 'FNR==3 && NF>2 {print FILENAME, $2; nextfile}' *.txt |parallel --colsep "t" 'mv {1} {2}'

awk iterate over all files in the location. We define the ' as the field separator. Whenever it reaches the third line and there are more than 2 fields (which should be if we have two ') it prints out the filename and the second field (which is the part between the first two ') delimited by a tab. Then it skipes to the next file.

The result is piped to parallel. parallel execute the mv command by replacing {1} and {2} with values given in the columns from the awk result.

Some notes:

• 
  nextfile is not available in all awkversions


• 
  

  whitespaces in a filename is never a good idea. You could replace them by an underscore if you change the awk command like this:

  
  
  

  awk -v FS="'" -v OFS="t" 'FNR==3 && NF>2 { gsub(" ", "_", $2); print FILENAME, $2; nextfile}' *.txt

  
  


• You should move or copy your new filenames to another folder. I'm not sure how awk will react if new files appear in the same folder during runtime.

for j in ./*.txt

do

i=$( sed -n '3p' "$j" | cut -d "'" -f2)

mv "$j" "$i"

done

It will search all the files in the current directory and will move this file to the new one.

for src in *.html; do

  { read -r x && read -r x && IFS="'" read -r x dst x; } < "$src" &&

     mv -- "$src" "$dst.html"

done

I would do such a thing in perl instead of putting together some slow and fragile tangle of subshells:

perl -e 'while(<>){

  sub no_rename { print "rename @_n" }

  next unless $. == 3;

  if(my ($f) = /DATA POPULATION +'''(.*?)'''/){

      $f =~ s/[^w]/_/g;

      no_rename $ARGV, $f or warn "rename $ARGV, $f: $!n";

  }

  close ARGV

}' files ...

You'll have to change no_rename to rename to make it actually do it, instead of showing it.

Sorry for the ugly '''; if you put that in a script file instead of one-liner, that should be simply:

/DATA POPULATION +'(.*?)'/

If you really want to create filenames with spaces, also add a s after the w in the s///g expression (and similar for other characters that could go in the filename -- by default, the script will replace everything but letters and digits with an underscore).