How to put specific filenames into a specific JSON format using bash or Perl?-CodePudding

Assuming I'm in the folder like this:

➜  tmp.lDrLPUOF ls
1.txt 2.txt 3.txt 1.zip 2.rb

I want to put all the filenames of text files into a specific JSON format like this:

{
  "": [
    {
      "title": "",
      "file": "1"
    },
    {
      "title": "",
      "file": "2"
    },
    {
      "title": "",
      "file": "3"
    }
  ]
}

Now I just know how to list all the filenames:

➜  tmp.lDrLPUOF ls *'.txt'
1.txt 2.txt 3.txt

Can I use bash or Perl to achieve this purpose? Thank you very much!

Edit

Thanks for @Charles Duffy and @Shawn 's great answers. But it's my fault to forget another important piece of information——time. I want to put the filenames into the resulting JSON per their creating time.

The creating time is as below:

➜  tmp.lDrLPUOF ls -lTr
total 0
-rw-r--r--  1 administrator  staff  0 Oct 12 09:35:05 2022 3.txt
-rw-r--r--  1 administrator  staff  0 Oct 12 09:35:08 2022 2.txt
-rw-r--r--  1 administrator  staff  0 Oct 12 09:35:12 2022 1.txt

So the resulting JSON I wanted should be like this:

{
  "": [
    {
      "title": "",
      "file": "3"
    },
    {
      "title": "",
      "file": "2"
    },
    {
      "title": "",
      "file": "1"
    }
  ]
}

CodePudding user response：

If installed, tree can be a good alternative to list the contents of directories as it can encode its output as well-defined JSON which comes in handy when dealing with strange file names (and especially when your desired output is JSON anyways).

tree -JtL 1 -P '*.txt'

[
  {"type":"directory","name":".","contents":[
    {"type":"file","name":"3.txt"},
    {"type":"file","name":"2.txt"},
    {"type":"file","name":"1.txt"}
  ]}
,
  {"type":"report","directories":0,"files":3}
]

tree -J outputs JSON
tree -t sorts by last modification time
tree -L 1 recurses only 1 level deep
tree -P '*.txt' reduces the the list to file pattern *.txt

Of course, you can also add more details, if needed, such as

tree -p includes file permissions
tree -u and tree -g include user and group names
tree -s includes the file size in bytes
tree -D --timefmt '%F %T' includes the last modification time

tree -JtL 1 -P '*.txt' -pusD --timefmt='%F %T'

[
  {"type":"directory","name":".","mode":"0755","prot":"drwxr-xr-x","user":"hustnzj","size":4096,"time":"2022-10-12 09:35:00","contents":[
    {"type":"file","name":"3.txt","mode":"0644","prot":"-rw-r--r--","user":"hustnzj","size":123,"time":"2022-10-12 09:35:05"},
    {"type":"file","name":"2.txt","mode":"0644","prot":"-rw-r--r--","user":"hustnzj","size":456,"time":"2022-10-12 09:35:08"},
    {"type":"file","name":"1.txt","mode":"0644","prot":"-rw-r--r--","user":"hustnzj","size":789,"time":"2022-10-12 09:35:12"}
  ]}
,
  {"type":"report","directories":0,"files":3}
]

A note regarding this comment: tree -t sorts by last modification time. There's also an option tree -c to sort by (and with tree -D to show time as) last status change instead, but there's no dedicated option (I know of) that uses creation/birth times (if supported by the file system).

Then, using that JSON output as input, you can employ jq for further filtering and formatting:

tree … | jq --arg ext '.txt' '
  {"": (first.contents | map(
    select(.type == "file") | {title: "", file: .name | rtrimstr($ext)}
  ))}
'

{
  "": [
    {
      "title": "",
      "file": "3"
    },
    {
      "title": "",
      "file": "2"
    },
    {
      "title": "",
      "file": "1"
    }
  ]
}

Demo

Note: This includes the filter select(.type == "file") as tree would also include the names of subdirectories. Drop it if you want them included.

CodePudding user response：

{ shopt -s nullglob; set -- *.txt; printf '%s\0' "$@"; } | jq -Rn '
  {"": [ input
         | split("\u0000")[]
         | select(. != "")
         | {"title": "",
            "file": . | rtrimstr(".txt")
           }
       ]
  }
'

Let's break this down into pieces.

On the bash side:

shopt -s nullglob tells the shell that if *.txt has no arguments, it should emit nothing at all, instead of emitting the string *.txt as a result.
set -- overwrites the argument list in the current context (because this is a block on the left-hand side of the pipeline that context is transient and won't change "$@" in code outside the pipe).
printf '%s\0' "$@" prints our arguments, with a NUL character after each one; if there are no arguments at all, it prints only a NUL.

On the jq side:

-R specifies that the input is raw data, not json.
-n specifies that we don't automatically consume any inputs, but will instead use input or inputs to specify where input should be read.
split("\u0000") splits the input on NULs. (This is important because the NUL is the only character that can't exist in a filename, which is why we used printf '%s\0' on the shell end; that way we work correctly with filenames with newlines, literal quotes, whitespace, and all the other weirdness that's able to exist).
select(. != "") ignores empty strings.
rtrimstr(".txt") removes .txt from the name.

Addendum: Sorting by mtime

The jq parts don't need to be modified here: to sort by mtime you can adjust only the shell. On a system with GNU find, sort and sed, this might look like:

find . -maxdepth 1 -type f -name '*.txt' -printf '%T@ %P\0' |
  sort -zn |
  sed -z -re 's/^[[:digit:].]  //g' |
  jq -Rn '

...followed by the same jq given above.

CodePudding user response：

Using just jq, any shell:

$ jq  -n --args '{"": [ $ARGS.positional[] | rtrimstr(".txt") | { title: "", file: . } ] }' *.txt 
{
  "": [
    {
      "title": "",
      "file": "1"
    },
    {
      "title": "",
      "file": "2"
    },
    {
      "title": "",
      "file": "3"
    }
  ]
}

The filenames passed on the command line (The expansion of *.txt are in the jq variable $ARGS.positional. For each one, remove the .txt extension and use the rest in a object of the desired structure.

Or with a perl one-liner:

$ perl -MJSON::PP -E 'say encode_json({"" => [ map { { title => "", file => s/\.txt$//r } } @ARGV ] })' *.txt
{"":[{"file":"1","title":""},{"title":"","file":"2"},{"file":"3","title":""}]}

CodePudding user response：

My take:

stat -c '%Y:%n' *.txt \
| sort -t: -n \
| cut -d: -f2- \
| xargs basename -s .txt \
| jq -s 'map({title: "", file: tostring}) | {"": .}'