Add numbers to the beginning of every line in a file
BashRow NumberBash Problem Overview
How can I add numbers to the beginning of every line in a file?
E.g.:
This is the text from the file.
Becomes:
000000001 This is 000000002 the text 000000003 from the file.
Bash Solutions
Solution 1 - Bash
Don't use cat or any other tool which is not designed to do that. Use the program:
> nl - number lines of files
Example:
$ nl --number-format=rz --number-width=9 foobar
$ nl -n rz -w 9 foobar # short-hand
Because nl is made for it ;-)
Solution 2 - Bash
AWK's printf, NR and $0 make it easy to have precise and flexible control over the formatting:
~ $ awk '{printf("%010d %s\n", NR, $0)}' example.txt
0000000001 This is
0000000002 the text
0000000003 from the file.
Solution 3 - Bash
You're looking for the nl(1) command:
$ nl -nrz -w9 /etc/passwd
000000001 root:x:0:0:root:/root:/bin/bash
000000002 daemon:x:1:1:daemon:/usr/sbin:/bin/sh
000000003 bin:x:2:2:bin:/bin:/bin/sh
...
-w9 asks for numbers nine digits long; -nrz asks for the numbers to be formatted right-justified with zero padding.
Solution 4 - Bash
cat -n thefile will do the job, albeit with the numbers in a slightly different format.
Solution 5 - Bash
Easiest, simplest option is
awk '{print NR,$0}' file
See comment above on why nl isn't really the best option.
Solution 6 - Bash
Here's a bash script that will do this also:
#!/bin/bash
counter=0
filename=$1
while read -r line
do
printf "%010d %s" $counter $line
let counter=$counter+1
done < "$filename"
Solution 7 - Bash
perl -pe 'printf "%09u ", $.' -- example.txt