How can I prepend a line number and tab to each line of a text file?

Question

How can I append a line number and tab to the beginning of each line of a text file?

Answer 1

awk '{printf "%d\t%s\n", NR, $0}' < filename

Answer 2

The nl command should do this, but it adds space before the line number too. It's part of Linux coreutils.

nl lines.txt
 1  $bkWTN
 2  $cV8$.

Answer 3

sed = test.txt | sed 'N;s/\n/\t/'

The command "sed =" will print the line number followed by a carriage return and then the next line.

The expression "N;s/\n/\t/" will take each line, get the next line (ie line number and the line), and replace the carriage return with a tab.

Answer 4

cat -n <yourfile> | perl -pe "s/^\s*(\d+)\s+/\1\t/"

cat -n adds linenumbers as " 123 linecontents" and that regexp modifies it to "linenumberTABlinecontents"

Answer 5

perl -pe "s/^/$.\t$_/" file.txt

or

perl -ne "print qq($.\t$_)" file.txt

Answer 6

Ok, since we are collecting ways to do this,

 grep -n . file.txt | sed 's/\(^[0-9]*\):/\1    /g'
 # this is a tab with Ctrl-V + Tab  =====>  ----

Answer 7

sed file.txt -e 's/^/\t/' | cat -n | sed -e 's/^\t//'

or for some non-GNU seds:

cat file.txt | sed -e 's/^/\\t/' | cat -n | sed -e 's/^\\t//'

Answer 8

How about

cat -n somefile.txt

?