[SOLVED] [bash] comma-separated output

boughtonp · 02-19-2020, 07:32 AM

xsv is a useful tool for CSV handling.

I've not used it in a while, but this (untested) might be another option:

Code:

input | xsv fmt --delimiter=' '

I've only glanced at the diff thread, but perhaps xsv's select or join options could help simplify some of that logic.

Although I I've just seen you mention AIX, so not sure if it's a viable option.

crts · 02-19-2020, 08:21 AM

Quote:

Originally Posted by boughtonp

xsv is a useful tool for CSV handling.

I've not used it in a while, but this (untested) might be another option:

Code:

input | xsv fmt --delimiter=' '

I've only glanced at the diff thread, but perhaps xsv's select or join options could help simplify some of that logic.

Although I I've just seen you mention AIX, so not sure if it's a viable option.

I participated in the thread that OP linked and if I remember correctly then OP is not allowed to install any 3rd party tools at all.

Quote:

Originally Posted by schneidz

(a little bit of history:
https://www.linuxquestions.org/quest...ns-4175663736/ )

Well, I guess then you can still not provide some more representative sample data, right? I am still unclear what you mean by more general solution. Do you want to read the data from a file?

schneidz · 02-19-2020, 09:34 AM

Quote:

Originally Posted by crts

I participated in the thread that OP linked and if I remember correctly then OP is not allowed to install any 3rd party tools at all.

Well, I guess then you can still not provide some more representative sample data, right? I am still unclear what you mean by more general solution. Do you want to read the data from a file?

the confusion was whether i was specifically looking for a c.s.v. output for ls. i was just using it as an example therefore ls -m doesnt help. i needed something that puts commas in place of any white-space or new-lines between strings for any generic comnand from piped input (without me having to worry about preceding or trailing commas which mash up sql in() clause.)

boughtonp · 02-19-2020, 10:08 AM

Quote:

Originally Posted by schneidz

i needed something that puts commas in place of any white-space or new-lines between strings for any generic comnand from piped input

Well whitespace is a group of characters which includes newline characters.

If you only care about space and newline the existing paste solution with tr seems simplest:

Code:

input | tr ' ' '\n' | paste -sd,

Otherwise, if AIX sed supports the -z argument, you can do it in a single sed call...

Replacing space (ascii 32) or newline (ascii 10) with a comma, then removing trailing comma:

Code:

input | sed -z 's/[\n ]/,/g; s/,$//'

Same thing, but replacing all sequential whitespace characters (ascii 9,10,11,13,32) with a comma:

Code:

input | sed -rz 's/\s+/,/g; s/,$//'

MadeInGermany · 02-19-2020, 04:33 PM

The following join function works in bash, ksh, zsh:

Code:

join(){
typeset delim=$1 tmpstr
shift || return
tmpstr=$(printf ",%s" "$@")
printf "%s\n" "${tmpstr#$delim}"
}

Now run it as

Code:

join "," *

crts · 02-19-2020, 04:54 PM

Quote:

Originally Posted by MadeInGermany

The following join function works in bash, ksh, zsh:

Code:

join(){
typeset delim=$1 tmpstr
shift || return
tmpstr=$(printf ",%s" "$@")
printf "%s\n" "${tmpstr#$delim}"
}

Now run it as

Code:

join "," *

If you want to use a variable, may I suggest a simple echo to avoid the parsing overhead of the second printf?

Code:

join() {
        typeset delim=$1 tmpstr
        shift || return
        printf -v tmpstr "$delim%s" "$@"
        echo "${tmpstr#$delim}"
}

It works in Bash, do not know about ksh and zsh since I do not use them.

MadeInGermany · 02-20-2020, 03:34 AM

Good point.
The -v is more efficient because it does not require a fork().
But it is bash-only.

BTW for robust functions I use printf not echo.
For example:

Code:

join "," -n

will not print the -n if echo interprets it as an option.

crts · 02-22-2020, 06:55 AM

Quote:

Originally Posted by MadeInGermany

BTW for robust functions I use printf not echo.
For example:

Code:

join "," -n

I always seem to forget about that. This problem has never backfired on and I have only encountered it when someone pointed it out. Maybe I should give more consideration to 'printf' in the future, but I guess bad habits die hard :)

David the H. · 02-23-2020, 08:51 AM

I always prefer to use shell built-ins as much as possible. And you can do a lot with them.

In this case, since we're dealing with lists of filenames, the go-to tools are arrays and globbing (assuming bash or similar shell that supports them).

Code:

$ flist=( * )                # note that the sort order may differ from ls -1
$ clist=$( IFS=, ; echo "${flist[*]}" )
$ echo "$clist"

or:

$ printf -v clist '%s,' *    #no need to bother with an array with printf
$ clist="${clist%,}"
$ echo "$clist"

For the first option, an array variable with * as its index expands to all of its elements, separated by the first character of IFS.

Unfortunately, due to the parsing sequence, you have to set IFS first as a separate command, before variable expansion. So in this case I have opted to expand the result in a subshell and transfer the output to a new variable, to avoid having the modified IFS affect the main shell.

The second option uses the printf idea from earlier, except that the superfluous comma is handled by again transferring the resulting string to a second variable, and using a simple parameter substitution to remove it.

edit1: Doh, I missed that MadeInGermany has already given this solution.

edit2: Just a heads-up, "join" is already the name of a coreutil application, albeit one with a completely different function.

MadeInGermany · 02-23-2020, 12:44 PM

You are right, a join utility exists! Did not think of it.
Suggested new unique name for my function: prtjoin