-1

I am trying to get a list of only directory names in order to store it in a variable for a foreach for processing later on.

However, just testing the ls first I am getting weird results.

For example: 

ls -1 /var/lib/mysql/ | grep -e '^d'
db_nagiosql
db_nagiosql_v32
discount-o-matic
drupal
drupal5

However, this does what it should do:

ls -l /var/lib/mysql | grep -e '^d' | awk '{print $9}'
alex
bugs
bugtracker
bugzilla
cacti
cerb5
db_nagiosql
db_nagiosql_v32
discount-o-matic
drupal
drupal5
earth
fft
final_function_test
firm_ware
flyspray
gallery2
graphics
jon
joomla
mysql
nconf
old_fft
opendocman
oreon
part-number
phpbb
phpbugtracker
phplist
postnuke
teldir
test
testing
vanilla
vision
wikidb
wordpress
zen

The issue is, I need this to be portable(ish) so the awk part I rather not have as it may not always be the ninth column. Why does the ls -1 not work while the ls -l /var/lib/mysql | grep -e '^d' | awk '{print $9}' does work?

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  • 1
    Why have you called grep in the first example, if you don't only want directories whose names start with d?
    – Michael Hampton
    Dec 18, 2015 at 17:11
  • That explains that lol. I only want to list directories. I thought the ^d does that? No files. No information. Just the name of the directory regardless of name listed one per line.
    – Jonathan
    Dec 18, 2015 at 17:14
  • 2
    No, this can't be true. You wrote a whole question on SF without doing some basic research (like reading the documentation) and realising that you had misread a basic command :(
    – user9517
    Dec 18, 2015 at 17:59
  • ls -1 with a number one does not do a long listing of the entries, so the first character being a d only means the file/directory name starts with a d not that it is a directory. if you did a -l (lower case L) instead of 1 your grep would work, but as @inukshuk's answer shows there are better ways to get just the directories
    – Eric Renouf
    Dec 18, 2015 at 17:59
  • I actually had done research but misread my own comments as to what ^d was doing. I forgot it was from the d in the permissions rather than directory type, thus why the long listing worked and not the ls -1, thus why talking amongst others is a great learning experience for catching such silly mistakes.
    – Jonathan
    Dec 18, 2015 at 19:50

2 Answers 2

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If you're trying to portably find all the directories you could use find like so:

 find /var/lib/mysql/ -maxdepth 1 -mindepth 1 -type d -exec basename {} \;

or if you have GNU (so not as portable)

 find /var/lib/mysql/ -maxdepth 1 -mindepth 1 -type d -printf "%f\n"

Assuming you want to further process these you might want to adapt what you're doing to be able to take the full path and let find help with -print0 and xargs -0 so you won't get tripped up with special characters in the path names. See why you shouldn't parse the output of ls for more info about the dangers of that road

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  • Problem with this it returns the parent directory mysql as top result, but a better approach than I had done.
    – Jonathan
    Dec 18, 2015 at 19:47
  • @Jonathan I updated my answer to fix the inclusion of the parent mysql directory
    – Eric Renouf
    Dec 18, 2015 at 20:05
  • Since these are the actual databases I would think the problem wouldn't occur, though I never tried making a mysql db with special chars. What I am ultimately doing, is mysqldumping all the individual databases so I can recover individual databases easier rather than having EVERYTHING in one sql file dump by doing a for loop to iterate all the directories stored in a local variable for iteration.
    – Jonathan
    Dec 18, 2015 at 20:11
  • @Jonathan first, you can put spaces in the names of databases like create database `with space`, but it seems to not use the space in the directory name at least on the version of mysql I have running. Second, just as a caution, the 2 find commands I provided actually still fall under the don't parse ls rule I quoted, even though they aren't using ls, they have the same problems unless you use the print0 or use the -exec to find but then it depends a little on what you do in the exec
    – Eric Renouf
    Dec 19, 2015 at 1:11
  • I'm essentially exporting the contents to a variable in a shell script so I can do a for each on it where it mysqldump each individual database from the list in the variable on a daily cron job.
    – Jonathan
    Dec 19, 2015 at 1:35
2

First, grep is matching a text pattern where ^d specifically matches all lines starting with the d character. When you do ls -l, the lines start with drwx if they are a directory, -rwx if they are a file, lrwx if they are a link, etc (give-or-take the read/write/execute permissions). When you ls -1, it's listing just the file or directory name with no other info, so grep'ing ^d will get you only files and directories that start with a d.

There are two ways to do what you're looking for:

To list only directories with the ls command, you need "ls -d */". To get your desired result, you list all the directories on one line, then remove the trailing / character if you want:

ls -1d */ | sed 's|/$||'

Or alternatively, you can use the ls -l command, grep for the directories like you did, and then awk the last column rather than the 9th column:

ls -l | grep ^d | awk '{print $NF}'
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2
  • In the last example you don't need the grep at all since awk can do pattern matching, e.g., `awk '/^d/ {print $NF}'
    – Eric Renouf
    Dec 18, 2015 at 18:01
  • I am going with ls -l /var/lib/mysql | awk '/^d/ {print $NF}' as this does exactly what I need and more simplified than having multiple pipes. Thank you.
    – Jonathan
    Dec 18, 2015 at 19:53

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