How can I find the first missing directory in a long path?

Question

Imagine I have a path that doesn't exist:

$ ls /foo/bar/baz/hello/world
ls: cannot access /foo/bar/baz/hello/world: No such file or directory

But let's say /foo/bar does exist. Is there a quick way for me to determine that baz is the breaking point in the path?

I'm using Bash.

Answer 1

One of my favourite utilties is namei, part of util-linux and hence generally present only on Linux:

$ namei /usr/share/foo/bar
f: /usr/share/foo/bar
 d /
 d usr
 d share
   foo - No such file or directory

But its output is not very parseable. So, if you just wish to point out something is missing, namei might be useful.

It's useful for troubleshooting general problems in accessing a path, since you can get it to state whether a component is a link or a mount point, as well as its permissions:

$ ln -sf /usr/foo/bar /tmp/
$ namei -lx /tmp/bar
f: /tmp/bar
Drwxr-xr-x root    root    /
Drwxrwxrwt root    root    tmp
lrwxrwxrwx muru    muru    bar -> /usr/foo/bar
Drwxr-xr-x root    root      /
drwxr-xr-x root    root      usr
                             foo - No such file or directory

The capital D indicates a mount point.

Answer 2

Given a canonical pathname, such as yours, this will work:

set -f --; IFS=/
for p in $pathname
do    [ -e "$*/$p" ] || break
      set -- "$@" "$p"
done; printf %s\\n "$*"

That prints through the last fully existing/accessible component of $pathname, and puts each of those separately into the arg array. The first nonexistent component is not printed, but it is saved in $p.

You might approach it oppositely:

until cd -- "$path" && cd -
do    case   $path  in
      (*[!/]/*)
              path="${path%/*}"
;;    (*)   ! break
      esac
done  2>/dev/null   && cd -

That will either return appropriately or will pare down $path as needed. It declines to attempt a change to /, but if successful will print both your current working directory and the directory to which it changes to stdout. Your current $PWD will be put in $OLDPWD as well.

Answer 3

Something like this (accounting for pathnames with embedded blanks):

#!/bin/sh
explain() {
    if [ -d "$1" ]
    then
        printf "\t%s: is a directory\n" "$1"
    elif [ -e "$1" ]
    then
        printf "\t%s: is not a directory\n" "$1"
    else
        printf "\t%s: does not exist\n" "$1"
    fi
}

for item in "$@"
do
    last=
    test="$item"
    printf "testing: '%s'\n" "$item"
    while [ ! -d "$test" ]
    do
        last="$test"
        test=$(dirname "$test")
        [ -z "$test" ] && break
    done
    if [ -n "$last" ]
    then
        explain "$test"
        explain "$last"
    else
        printf "\t%s: ok\n" "$item"
    fi
done

Answer 4

Just an alternative solution for bash, assuming the path is an absolute path (starts with /) :

#!/bin/bash

pathname="$1"

IFS='/' read -r -a p <<<"${pathname#/}"

pa=""    max="${#p[@]}"    i=0
while (( i<"$max" )); do
      pa="$pa/${p[i++]}"
      if     [[ ! -e $pa ]]; then
             printf 'failed at: \t"%s"\t"%s"\n' "${pa##*/}" "${pa}"
             break
      fi
done

---

$ ./script "/foo/ba r/baz/hello/world"
failed at:      "hello"        "/foo/ba r/baz/hello"

Answer 5

(( dirct=$(echo ${dir}|tr "/" " "|wc -w)+1 ))
i=2
while [ ${i} -le ${dirct} ]
do
  sdir=$(echo ${dir}|cut -d/ -f1,${i})
  if [ ! -d ${sdir} ]
  then
    echo "Path is broken at ${sdir}"
  fi
  (( i++ ))
done

it is not simple but you can put it in a script, make it executable and stick it somewhere in your path, if you are going to use it frequently.

Caveat emptor: If your directory name at any level contains a space character, this will NOT work.