can find search multiple variations of order for specified input vars

Question

I want to be able to run a find that uses all possible variations of order of a user's input values ($1 $2 $3 .. $9 or the value of $# really) to see if a file exists. But once the user enters just 3 params (search patterns) the find commands starts to get a little unwieldy:

docs=($(find /dir1 /dir2 -type f -iname "*$1*$2*$3" -o -iname "*$1*$3*$2" -o -iname "*$2*$1*$3" -o -iname "*$2*$3*$1*" -o -iname "*$3*$1*$2*" -o -iname "*$3*$2*$1*" ))

Is there a way to tell find to take specified multiple patterns and search every possible variation of order to see if a file exists? For most cases I imagine only 2-4 input params will be fed by the user, but I want to allow for searches using upto 9 input vars, and I hate to imagine what a find command when $# = 9 might look like.

Answer 1

I love your question. You need to generate all permutations of the positional parameters. Lots of fun:

#!/bin/bash

perms() {
   if (($#==1)); then 
      ary_perms=( "$1" )
      return
   fi
   local i
   local ary=()
   for ((i=1;i<=$#;++i)); do
      perms "${@:1:i-1}" "${@:i+1}"
      ary+=( "${ary_perms[@]/#/${!i}$sep}" )
   done
   ary_perms=( "${ary[@]}" )
}

sep='*'
perms "$@"

searchargs=()
for s in "${ary_perms[@]}"; do
   searchargs+=( -o -iname "*$s*" )
done
searchargs=( "${searchargs[@]:1}" )

find /dir1 /dir2 "${searchargs[@]}"

The function perm generates all permutations of the given arguments, in a way 100% safe regarding funny symbols (spaces, newlines, etc.). It's a straightforward recursive function so it might explode quickly if you feed it with too many arguments, but hey, you don't want to generate all the permutations of a set with 40 elements, do you?

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Now this is of course a very bad method! You certainly don't want to do this.

Instead of

find /dir1 /dir2 -type f -iname "*$1*$2*$3*" -o -iname "*$1*$3*$2*" -o -iname "*$2*$1*$3*" -o -iname "*$2*$3*$1*" -o -iname "*$3*$1*$2*" -o -iname "*$3*$2*$1*"

why not just this?

find /dir1 /dir2 -type f -iname "*$1*" -iname "*$2*" -iname "*$3*"

(there's an implicit and between the -iname's).

If you need a script to build up the search command:

#!/bin/bash

searchargs=()
for i; do
    searchargs+=( -iname "*$i*" )
done
find /dir1 /dir2 -type f "${searchargs[@]}"

much better, eh?

Of course this is not strictly equivalent to the previous mumbo with permutations, if you have repeated arguments. But hey, who cares, really? code simplicity wins here.

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Oh, a final remark, doing:

docs=( $(find ...) )

is very bad (think of filenames with spaces).