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Tzury Bar Yochay
Asked: 2011-03-10 01:00:08 +0800 CST

find files their name is smaller or greater than a given parameter

  • 772

Say that in a given directory I got

tzury@x200:~/Desktop/sandbox$ ls -l
total 20
drwxr-xr-x 2 tzury tzury 4096 2011-03-09 10:19 N00.P000
drwxr-xr-x 2 tzury tzury 4096 2011-03-09 10:19 N00.P001
drwxr-xr-x 2 tzury tzury 4096 2011-03-09 10:19 N00.P002
drwxr-xr-x 2 tzury tzury 4096 2011-03-09 10:19 N00.P003
drwxr-xr-x 2 tzury tzury 4096 2011-03-09 10:19 N00.P004
drwxr-xr-x 2 tzury tzury 4096 2011-03-09 10:19 N01.P000
drwxr-xr-x 2 tzury tzury 4096 2011-03-09 10:19 N01.P001
drwxr-xr-x 2 tzury tzury 4096 2011-03-09 10:19 N01.P002

I seek for a bash way to grab the list of files which their name is either grater or smaller than a given parameter, for instance:

$ my_finder lt N00.P003

shall return N00.P000, N00.P001 and N00.P002

$ my_finder gt N00.P003

shall return N00.P004, N01.P000, N01.P001 and N01.P002

I was thinking of iterating over for name in $(ls) and while $name != $2 but believe there are more elegant way of doing so

bash find

3 Answers

  1. Best Answer

    Never ever iterate over ls output!

    Here's my suggestion:

    for fn in *; do test "$fn" -$1 "$2" && echo "$fn"; done

    Edit:

    Sorry. The above works only if $fn and $2 are numeric. You'll have to replace -$1 with $op, and prepend a selector in front of the loop. op="<" or op=">" depending on $1 is lt or gt, respectively.

    • 3

  2. Unfortunately for this technique, /usr/bin/test doesn't support STRING > STRING, however the shell builtin test does so we have to invoke the shell in order to be able to use find -exec and avoid a loop:

    find $PWD -type f -exec sh -c 'test "{}" "<" "$PWD/N00.P004"' \; -print

    The question remains whether spawning a shell repeatedly is more efficient than running a loop. However, the chief advantage to using this technique is that you can do recursive processing without a pipe.

    You can create a function that uses this technique and allows you to use gt and lt instead of having to pass quoted < or >:

    my_finder () { 
    local op=$1
    case "$op" in
        "gt") op='>';;
        "lt") op='<';;
           *) echo "Invalid operator"; return 1;;
    esac
    find $PWD -type f -exec sh -c 'test "{}" "$op" "$PWD/$2"' \; -print
}

    Usage:

    $ my_finder gt N00.P003
/home/tzury/Desktop/sandbox/N00.P004
/home/tzury/Desktop/sandbox/N01.P000
/home/tzury/Desktop/sandbox/N01.P001
/home/tzury/Desktop/sandbox/N01.P002
    • 2 
  3. for num in {001..003} ;do ls N00.P"$num"; done

    Replace 003 with limit you want to put.

    • 1