Grep the first number in a line

Question

I have a file that has lines of numbers and a file:

    2    20    3    file1.txt
    93   21    42   file2.txt
    52   10    12   file3.txt

How do I use grep, awk, or some other command to just give me the first numbers of each line so that it will only display:

2
93
52

Thanks.

cdarke · Accepted Answer · 2016-04-20T07:40:58.027

9

So many ways to do this. Here are some (assuming the input file is gash.txt):

awk '{print $1}' gash.txt

or using pure bash:

while read num rest
do
    echo $num
done < gash.txt

or using "classic" sed:

sed 's/[ \t]*\([0-9]\{1,\}\).*/\1/' gash.txt

or using ERE with sed:

sed -E 's/[ \t]*([0-9]+).*/\1/' gash.txt

Using cut is problematic because we don't know if the whitespace is spaces or tabs.

By the way, if you want to add the total number of lines:

awk '{total+=$1} END{print "Total:",total}' gash.txt

edited Apr 20 '16 at 07:40

answered Apr 20 '16 at 07:05

cdarke

Thanks, you read my mind with the total :) – Arnold Hotz Apr 20 '16 at 07:17
1

Also, note that if you pass multiple files to `wc`, it will print total by default. – anishsane Apr 20 '16 at 07:33
Thanks! this worked for me! My text is stored in a variable so to run the command on it I did: `awk '{print $1}' <<< "$variable_string"` – Eyal Gerber Sep 11 '22 at 13:26

blackSmith · Answer 2 · 2016-04-20T07:22:38.613

6

You can use this:

grep -oE '^\s*[0-9]+' filename

To handle the leading spaces, I'm currently out of options. You better accept the awk answer.

edited Apr 20 '16 at 07:22

answered Apr 20 '16 at 07:03

blackSmith

1

You don't need the first set of `[ ]` for a single space (although it does aid readability), but it might be better to consider `[ \t]*`, or `\s*` since we don't know the file format. – cdarke Apr 20 '16 at 07:09
@cdarke : thanks, I'm updating the answer. – blackSmith Apr 20 '16 at 07:13
Thats fine, I just wanted the numbers! – Arnold Hotz Apr 20 '16 at 07:27

score 2 · Answer 3 · answered Apr 20 '16 at 07:04

2

You can use awk

awk '{print $1}' file

answered Apr 20 '16 at 07:04

oliv

3 Answers3