How to match "field 5 through the end of the line" (for example, in awk) - awk

Question

I want to pretty-print the output of a find-like script that would take input like this:
- 2015-10-02 19:45 102 /My Directory/some file.txt
and produce something like this:
- 102 /My Directory/some file.txt
In other words: "f" (for "file"), file size (right-justified), then pathname (with an arbitrary number of spaces).
This would be easy in awk if I could write a script that takes $1, $4, and "everything from $5 through the end of the line".
I tried using the awk construct substr($0, index($0, $8)), which I thought meant "everything starting with field $8 to the end of $0".
Using index() in this way is offered as a solution on linuxquestions.org and was upvoted 29 times in a stackoverflow.com thread.
On closer inspection, however, I found that index() does not achieve this effect if the starting field happens to match an earlier point in the string. For example, given:
-rw-r--r-- 1 tbaker staff 3024 2015-10-01 14:39 calendar
-rw-r--r-- 1 tbaker staff 4062 2015-10-01 14:39 b
-rw-r--r-- 1 tbaker staff 2374 2015-10-01 14:39 now or later
Gawk (and awk) get the following results:
$ gawk '{ print index($0, $8) }' test.txt
49
15
49
In other words, the value of $8 ('b') matches at index 15 instead of 49 (i.e., like most of the other filenames).
My issue, then is how to specify "everything from field X to the end of the string".
I have re-written this question in order to make this clear.

Answer 1

Looks to me like you should just be using the "stat" command rather than "ls", for the reasons already commented upon:
stat -c "f%15s %n" *
But you should double-check how your "stat" operates; it apparently can be shell-specific.

Answer 2

The built-in awk function index() is sometimes recommended as a way
to print "from field 5 through the end of the string" [1, 2, 3].
In awk, index($0, $8) does not mean "the index of the first character of
field 8 in string $0". Rather, it means "the index of the first occurrence in
string $0 of the string value of field 8". In many cases, that first
occurrence will indeed be the first character in field 8 but this is not the
case in the example above.
It has been pointed out that parsing the output of ls is generally a bad
idea [4], in part because implementations of ls significantly differ in output.
Since the author of that note recommends find as a replacement for ls for some uses,
here is a script using find:
find $# -ls |
sed -e 's/^ *//' -e 's/ */ /g' -e 's/ /|/2' -e 's/ /|/2' -e 's/ /|/4' -e 's/ /|/4' -e 's/ /|/6' |
gawk -F'|' '{ $2 = substr($2, 1, 1) ; gsub(/^-/, "f", $2) }
{ printf("%s %15s %s\n", $2, $4, $6) }'
...which yields the required output:
f 4639 /Users/foobar/uu/a
f 3024 /Users/foobar/uu/calendar
f 2374 /Users/foobar/uu/xpect
This approach recursively walks through a file tree. However, there may of course be implementation differences between versions of find as well.
http://www.linuxquestions.org/questions/linux-newbie-8/awk-print-field-to-end-and-character-count-179078/
How to print third column to last column?
Print Field 'N' to End of Line
http://mywiki.wooledge.org/ParsingLs

Answer 3

Maybe some variation of find -printf | awk is what you're looking for?
$ ls -l tmp
total 2
-rw-r--r-- 1 Ed None 7 Oct 2 14:35 bar
-rw-r--r-- 1 Ed None 2 Oct 2 14:35 foo
-rw-r--r-- 1 Ed None 0 May 3 09:55 foo bar
$ find tmp -type f -printf "f %s %p\n" | awk '{sub(/^[^ ]+ +[^ ]/,sprintf("%s %10d",$1,$2))}1'
f 7 tmp/bar
f 2 tmp/foo
f 0 tmp/foo bar
or
$ find tmp -type f -printf "%s %p\n" | awk '{sub(/^[^ ]+/,sprintf("f %10d",$1))}1'
f 7 tmp/bar
f 2 tmp/foo
f 0 tmp/foo bar
It won't work with file names that contain newlines.