Globbing/pathname expansion with colon as separator

Question

How can I convert a string containing glob characters such as

/var/lib/gems/*/bin

into a colon-separated string of filenames (i.e. PATH compatible) matching the pattern?

i.e. echo /var/lib/gems/*/bin will return

/var/lib/gems/1.8/bin /var/lib/gems/1.9.1/bin

I want

/var/lib/gems/1.8/bin:/var/lib/gems/1.9.1/bin

instead.

The obvious approach is simply to replace the space character with ':' via tr, but that doesn't work if the filename itself contains the space character.

score 20 · Accepted Answer · answered Aug 08 '10 at 21:41

20

Actually, I thought of a better solution: use a shell function.

function join() {
    local IFS=$1
    shift
    echo "$*"
}

mystring=$(join ':' /var/lib/gems/*/bin)

answered Aug 08 '10 at 21:41

Sean

29,130
4
80
105

score 13 · Answer 2 · answered Aug 07 '10 at 13:39

This should do it for you:

dirs=(/var/lib/gems/*/bin)    # put filenames (dirnames) in an array
saveIFS=$IFS IFS=':'          # set the Internal Field Separator to the desired delimiter
dirs=("${dirs[*]}")           # convert the array to a scalar with the new delimiter
IFS=$saveIFS                  # restore IFS

score 6 · Answer 3 · answered Aug 07 '10 at 15:07

6

PATH="$(printf "%s:" /usr/*/bin)"
PATH="${PATH%:}"

answered Aug 07 '10 at 15:07

timo

61
1

3

This works, but I'd use a different variable. You can also do the inital assignment this way: `printf -v varname "%s:" /var/lib/gems/*/bin` – Dennis Williamson Aug 07 '10 at 17:30
Almost perfect. I think I like piping to sed to remove the trailing colon though ala http://stackoverflow.com/a/5074995/69002 – Mat Schaffer Nov 19 '13 at 19:52
@DennisWilliamson That's a beautiful oneliner. IMHO it should be the top answer. – Tobias Fendin Feb 06 '21 at 12:32

score 4 · Answer 4 · answered Jan 02 '19 at 19:04

4

No need to mess with IFS, zsh can join arrays with a simple variable flag:

dirs=(/var/lib/gems/*/bin(N))
dirs=${(j.:.)dirs}

The (N) on the first line suppresses a warning if there are no files; the (j.:.) joins the array with :s. Works with 0, 1, or multiple matches.

answered Jan 02 '19 at 19:04

Kevin

53,822
15
101
132

1

@Michaël not that I've found, though ZSH does often still surprise me so I can't say for sure that it can't. – Kevin Sep 17 '20 at 00:18

score 3 · Answer 5 · answered Aug 07 '10 at 21:11

3

It's pretty trivial if you drop into Perl:

perl -e 'print join ":", @ARGV' /var/lib/gems/*/bin

Or Python:

python -c 'import sys; print ":".join(sys.argv[1:])' /var/lib/gems/*/bin

Or any number of other popular scripting languages.

answered Aug 07 '10 at 21:11

Sean

29,130
4
80
105

It seems as though this might be the best approach overall (the IFS fiddling is a bit messy), although it is a shame to have have to use an external program... – mjs Aug 08 '10 at 07:58
definitely the way to go if you want a one-liner – mdup Apr 18 '13 at 08:07

score 3 · Answer 6 · answered Dec 11 '18 at 16:56

3

without saving IFS and command substitution

dirs=(/var/lib/gems/*/bin) ; IFS=: eval 'dirs="${dirs[*]}"'

answered Dec 11 '18 at 16:56

pal

618
4
9

score 2 · Answer 7 · answered Aug 07 '10 at 13:28

2

printf "%s\n" /var/lib/gems/*/bin | tr "\n" ":"

answered Aug 07 '10 at 13:28

ghostdog74

327,991
56
259
343

Close! But if there's only one match, you get a colon at the end: "/var/lib/gems/1.9.1/bin:". (And if there's no match, a single colon.) – mjs Aug 07 '10 at 13:40

score 1 · Answer 8 · answered Sep 22 '17 at 13:28

1

Another oneliner: printf "%s\n" /var/lib/gems/*/bin | paste -s -d':'

But @timo's answer is better in my opinion.

answered Sep 22 '17 at 13:28

domen

1,819
12
19

Globbing/pathname expansion with colon as separator

8 Answers8

Linked