Using sed/awk to remove anything after first space

Question

aaaaaaaa 09  
bbbbbbbb 90   
ccccccccccccccc  89  
ddddd 09

Using sed/awk/replace, in the above text I want to remove anything that comes after the first space in each line. For example the output will be:

aaaaaaaa  
bbbbbbbb    
ccccccccccccccc  
ddddd

any help will be appreciated.

score 49 · Answer 1 · edited Jun 09 '14 at 08:49

Sed

sed 's/\s.*$//'

Grep

grep -o '^\S*'

Awk

awk '{print $1}'

As pointed out in the comments, -o isn't POSIX; however both GNU and BSD have it, so it should work for most people.

Also, \s/\S may not be on all systems, if yours doesn't recognize it you can use a literal space, or if you want space and tab, those in a bracket expression ([...]), or the [[:blank:]] character class (note that strictly speaking \s is equivalent to [[:space:]] and includes vertical spacing characters as well like CR, LF or VT which you probably don't care about).

The awk one assumes the lines don't start with a blank character.

Stéphane Chazelas · Answer 2 · 2016-04-04T19:24:43.540

19

cut -d ' ' -f 1 < your-file

would be the most efficient.

edited Apr 04 '16 at 19:24

answered Nov 05 '13 at 22:36

Stéphane Chazelas

544,893

cut may be the best solution for problems this simple. I would reserve awk (or perl) for more complex matching. – ChuckCottrill Nov 05 '13 at 22:44
@StéphaneChazelas Looking at the man-page for cut, I can't tell if it will accept any sort of regex syntax. Do you have any idea whether or not it will, and if so, which type(s)? sry to bother and thanks. – Nate T Sep 18 '21 at 13:40
@NateT, no only single characters and with several implementations, even limited to singe byte characters only. – Stéphane Chazelas Sep 18 '21 at 16:02

score 6 · Answer 3 · edited Jun 06 '14 at 11:26

6

awk '{print $1}' file

or

sed 's/ .*//'

edited Jun 06 '14 at 11:26

mikeserv

58,310

answered Nov 05 '13 at 22:34

jlliagre

61,204

score 1 · Answer 4 · answered Jun 06 '14 at 14:12

1

And the one through perl,

$ perl -pe 's/^([^ ]+) .*$/\1/' file
aaaaaaaa
bbbbbbbb
ccccccccccccccc
ddddd

Through GNU grep,

$ grep -oP '^[^ ]*' file
bbbbbbbb
ccccccccccccccc
ddddd

answered Jun 06 '14 at 14:12

Avinash Raj

3,703

Using sed/awk to remove anything after first space

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