Check if a directory exists recursively reversing the path

I am kind of confused here ! I am not sure how to put forth the question .

May be with an example .

I am in the process of writing a bash script which checks if a specific folder named "FNS" is in the current directory . To check if the file exists ,I do this.

        FOLDER=FNS
        if [ -f $FOLDER ];
        then
        echo "File $FOLDER exists"
        else
        # do the thing
        fi

The problem arises If the file doesnt exists ! I want the script to take a note of the current path and move back a directory [ I meant cd .. in the command line ,I am not sure if I am using the correct vocabulary here] and check if the file exists and if not, again move back one step, until the directory in which it exist shows up [ it is sure to exist ] .When found store the path in a variable . The present directory of execution should not change.I tried passing the pwd to a variable and cutting till the last slash and some other stuffs without success !

Hope I can do something in this regard . Like always suggestions,algorithms and work arounds are welcome :)

---

试试这个，用圆括号启动一个子shell，这样cd命令不会改变当前shell的当前目录

(while [ ! -d "$FOLDER" ];do cd ..;done;pwd)

---

The bash pushd and popd built-in commands could help you. In pseudocode:

function FolderExists() { ... }

cds = 0
while (NOT FolderExists) {
    pushd ..
    cds=cds+1;
}

store actual dir using pwd command

for(i=0;i<cds;i++) {
    popd
}

---

One way using perl .

Content of script.pl (the directory is hard-coded but it's easy to modify the program to read it as an argument):

use warnings;
use strict;
use File::Spec;
use List::Util qw|first|;

## This variable sets to 1 after searching in the root directory.
my $try;

## Original dir to begin searching.
my $dir = File::Spec->rel2abs( shift ) or die;

do {
    ## Check if dir 'FNS' exists in current directory. Print
    ## absolute dir and finish in that case.
    my $d = first { -d && m|/FNS$| } <$dir/*>;
    if ( $d ) { 
        printf qq|%sn|, File::Spec->rel2abs( $d );    
        exit 0;
    }   

    ## Otherwise, goto up directory and carry on the search until
    ## we reach to root directory.
    my @dirs = File::Spec->splitdir( $dir );
    $dir = File::Spec->catdir( @dirs[0 .. ( $#dirs - 1 || 0 )] )
} while ( $dir ne File::Spec->rootdir || $try++ == 0);

Run it with a directory where the search will begin. It can be relative or absolute path. Like this:

perl script.pl /home/birei/temp/dev/everychat/

or

perl script.pl .

It will print the absolute path if found the directory. An example of my test:

/home/birei/temp/FNS

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