I used this command to display the first result of files in my directory.
ls | head -n 1
My simple question is, how can I modify this command to display say the nth result?
Thanks!
You could use sed to select a single line, for example line 12:
ls | sed -n 12p
Option -n asks sed not to print every line (which is what it normally does), and 12p asks to print the pattern space when the address is 12.
There may be better ways to do this, but this is probably the easiest: ls | head -<n> | tail -1
I have this in my .bashrc.
lsn () {
ls ${@:2} | head -n $1 | tail -n 1
}
This is called as such: lsn 4 for example. The $2 allows you to use
options on ls so lsn 4 -lah is also valid.
Note: when using the -l flag on ls there is an additional line at the top of the result. Which would skew this function's result.
-
2It would be more general to do
ls "$@"to passlsn's arguments down tols. Of course, after usingshiftto take out$1. – Kaz Jul 7 '15 at 19:31 -
With zsh and glob qualifiers:
ls -d -- *([7])
or
print -rl -- *([7])
will print the 7th file from the list of files sorted by name.
ls -d -- *(om[7])
or
print -rl -- *(om[7])
will print the 7th file from the list of files sorted by mtime (newest first - similar to extracting the 7th entry from ls -t output).
Ideally, if you're processing ls output, you should use something like ls -q | command(s) where -q prints ? instead of funky chars (like newlines) and command(s) processes only N lines of output, prints the Nth and then stops.
With tail and head (added nl for clarity). Let's fetch the fifth line :
ychaouche@ychaouche-PC ~ $ ls | nl
1 total 8.3M
2 -rw-r--r-- 1 ychaouche ychaouche 20K Jul 8 15:53 2.docx
3 -rw-r--r-- 1 ychaouche ychaouche 20K Jul 8 15:53 3.docx
4 drwxr-xr-x 2 ychaouche ychaouche 4.0K Jul 7 10:11 AUDIO
5 drwxr-xr-x 3 ychaouche ychaouche 4.0K May 28 09:33 BACKUPS
6 drwxr-xr-x 6 ychaouche ychaouche 4.0K May 17 13:49 BZR
7 drwxr-xr-x 6 ychaouche ychaouche 4.0K Jun 15 17:10 CODE
8 drwxr-xr-x 2 ychaouche ychaouche 4.0K May 25 10:24 Desktop
9 -rw-r--r-- 1 ychaouche ychaouche 34K Dec 2 2014 dget_problem.ods
10 drwxr-xr-x 12 ychaouche ychaouche 4.0K Jul 7 10:00 DOCUMENTS
11 drwx------ 2 ychaouche ychaouche 4.0K Apr 6 11:39 Downloads
12 drwxr-xr-x 16 ychaouche ychaouche 4.0K Jul 12 11:06 DOWNLOADS
13 drwxr-xr-x 6 ychaouche ychaouche 4.0K Jun 22 15:38 IMAGES
14 -rw-r--r-- 1 ychaouche ychaouche 690 Jan 25 14:25 IT_Alias.vcf
15 drwxr-xr-x 4 ychaouche ychaouche 4.0K Dec 2 2014 MACONF
16 -rw-r--r-- 1 ychaouche ychaouche 6.2M May 12 10:44 mtr.ogv
17 drwxr-xr-x 4 ychaouche ychaouche 4.0K Jan 5 2015 MUSIQUE
18 drwxr-xr-x 2 ychaouche ychaouche 4.0K Mar 2 16:29 NOTES
19 -rw-r--r-- 1 ychaouche ychaouche 2.0M May 12 10:42 out.ogv
20 -rw-r--r-- 3 ychaouche ychaouche 62K Apr 2 2014 php-mode.el
21 drwxr-xr-x 2 ychaouche ychaouche 4.0K Apr 8 13:25 Pictures
22 drwxr-xr-x 2 ychaouche ychaouche 4.0K Jan 6 2015 Projects
23 -rw-r--r-- 1 ychaouche ychaouche 353 Jan 12 2015 proxylog.dat
24 drwxr-xr-x 2 ychaouche ychaouche 4.0K Mar 19 15:35 public_html
25 -rw-r--r-- 1 ychaouche ychaouche 21 Nov 23 2014 registrationcode
26 drwxr-xr-x 6 ychaouche ychaouche 4.0K Jun 21 10:55 REPOS
27 drwxr-xr-x 2 ychaouche ychaouche 4.0K Jul 20 10:56 SCRIPTS
28 drwxr-xr-x 8 ychaouche ychaouche 4.0K Jun 11 10:36 SRV
29 drwxr-xr-x 14 ychaouche ychaouche 4.0K Jun 30 16:26 TMP
30 drwxr-xr-x 5 ychaouche ychaouche 4.0K Jun 28 16:56 VIDEOS
31 drwxr-xr-x 7 ychaouche ychaouche 4.0K Mar 18 11:35 VirtualBox VMs
32 drwxr-xr-x 3 ychaouche ychaouche 4.0K Jan 22 14:28 VIRTUALENVS
33 drwxr-xr-x 2 ychaouche ychaouche 4.0K Jul 7 12:24 WTMP
ychaouche@ychaouche-PC ~ $
This will jump to the fifth line :
ychaouche@ychaouche-PC ~ $ ls | nl | tail -n +5
5 drwxr-xr-x 3 ychaouche ychaouche 4.0K May 28 09:33 BACKUPS
6 drwxr-xr-x 6 ychaouche ychaouche 4.0K May 17 13:49 BZR
7 drwxr-xr-x 6 ychaouche ychaouche 4.0K Jun 15 17:10 CODE
8 drwxr-xr-x 2 ychaouche ychaouche 4.0K May 25 10:24 Desktop
9 -rw-r--r-- 1 ychaouche ychaouche 34K Dec 2 2014 dget_problem.ods
10 drwxr-xr-x 12 ychaouche ychaouche 4.0K Jul 7 10:00 DOCUMENTS
11 drwx------ 2 ychaouche ychaouche 4.0K Apr 6 11:39 Downloads
12 drwxr-xr-x 16 ychaouche ychaouche 4.0K Jul 12 11:06 DOWNLOADS
13 drwxr-xr-x 6 ychaouche ychaouche 4.0K Jun 22 15:38 IMAGES
14 -rw-r--r-- 1 ychaouche ychaouche 690 Jan 25 14:25 IT_Alias.vcf
15 drwxr-xr-x 4 ychaouche ychaouche 4.0K Dec 2 2014 MACONF
16 -rw-r--r-- 1 ychaouche ychaouche 6.2M May 12 10:44 mtr.ogv
17 drwxr-xr-x 4 ychaouche ychaouche 4.0K Jan 5 2015 MUSIQUE
18 drwxr-xr-x 2 ychaouche ychaouche 4.0K Mar 2 16:29 NOTES
19 -rw-r--r-- 1 ychaouche ychaouche 2.0M May 12 10:42 out.ogv
20 -rw-r--r-- 3 ychaouche ychaouche 62K Apr 2 2014 php-mode.el
21 drwxr-xr-x 2 ychaouche ychaouche 4.0K Apr 8 13:25 Pictures
22 drwxr-xr-x 2 ychaouche ychaouche 4.0K Jan 6 2015 Projects
23 -rw-r--r-- 1 ychaouche ychaouche 353 Jan 12 2015 proxylog.dat
24 drwxr-xr-x 2 ychaouche ychaouche 4.0K Mar 19 15:35 public_html
25 -rw-r--r-- 1 ychaouche ychaouche 21 Nov 23 2014 registrationcode
26 drwxr-xr-x 6 ychaouche ychaouche 4.0K Jun 21 10:55 REPOS
27 drwxr-xr-x 2 ychaouche ychaouche 4.0K Jul 20 10:56 SCRIPTS
28 drwxr-xr-x 8 ychaouche ychaouche 4.0K Jun 11 10:36 SRV
29 drwxr-xr-x 14 ychaouche ychaouche 4.0K Jun 30 16:26 TMP
30 drwxr-xr-x 5 ychaouche ychaouche 4.0K Jun 28 16:56 VIDEOS
31 drwxr-xr-x 7 ychaouche ychaouche 4.0K Mar 18 11:35 VirtualBox VMs
32 drwxr-xr-x 3 ychaouche ychaouche 4.0K Jan 22 14:28 VIRTUALENVS
33 drwxr-xr-x 2 ychaouche ychaouche 4.0K Jul 7 12:24 WTMP
ychaouche@ychaouche-PC ~ $
Then, obviously head -1
ychaouche@ychaouche-PC ~ $ ls | nl | tail -n +5 | head -1
5 drwxr-xr-x 3 ychaouche ychaouche 4.0K May 28 09:33 BACKUPS
ychaouche@ychaouche-PC ~ $
