Check if passed argument is file or directory in B

问题:

I'm trying to write an extremely simple script in Ubuntu which would allow me to pass it either a filename or a directory, and be able to do something specific when it's a file, and something else when it's a directory. The problem I'm having is when the directory name, or probably files too, has spaces or other escapable characters are in the name.

Here's my basic code down below, and a couple tests.

#!/bin/bash

PASSED=$1

if [ -d "${PASSED}" ] ; then
    echo "$PASSED is a directory";
else
    if [ -f "${PASSED}" ]; then
        echo "${PASSED} is a file";
    else
        echo "${PASSED} is not valid";
        exit 1
    fi
fi

And here's the output:

andy@server~ $ ./scripts/testmove.sh /home/andy/
/home/andy/ is a directory

andy@server~ $ ./scripts/testmove.sh /home/andy/blah.txt
/home/andy/blah.txt is a file

andy@server~ $ ./scripts/testmove.sh /home/andy/blah\ with\ a\ space.txt
/home/andy/blah with a space.txt is not valid

andy@server~ $ ./scripts/testmove.sh /home/andy\ with\ a\ space/
/home/andy with a space/ is not valid

All of those paths are valid, and exist.

回答1:

That should work. I am not sure why it's failing. You're quoting your variables properly. What happens if you use this script with double [[ ]]?

if [[ -d $PASSED ]]; then
    echo "$PASSED is a directory"
elif [[ -f $PASSED ]]; then
    echo "$PASSED is a file"
else
    echo "$PASSED is not valid"
    exit 1
fi

Double square brackets is a bash extension to [ ]. It doesn't require variables to be quoted, not even if they contain spaces.

Also worth trying: -e to test if a path exists without testing what type of file it is.

回答2:

At least write the code without the bushy tree:

#!/bin/bash

PASSED=$1

if   [ -d "${PASSED}" ]
then echo "${PASSED} is a directory";
elif [ -f "${PASSED}" ]
then echo "${PASSED} is a file";
else echo "${PASSED} is not valid";
     exit 1
fi

When I put that into a file "xx.sh" and create a file "xx sh", and run it, I get:

$ cp /dev/null "xx sh"
$ for file in . xx*; do sh "$file"; done
. is a directory
xx sh is a file
xx.sh is a file
$

Given that you are having problems, you should debug the script by adding:

ls -l "${PASSED}"

This will show you what ls thinks about the names you pass the script.

回答3:

Using -f and -d switches on /bin/test:

F_NAME="${1}"

if test -f "${F_NAME}"
then                                   
   echo "${F_NAME} is a file"
elif test -d "${F_NAME}"
then
   echo "${F_NAME} is a directory"
else                                   
   echo "${F_NAME} is not valid"
fi

回答4:

A more elegant solution

echo "Enter the file name"
read x
if [ -f $x ]
then
    echo "This is a regular file"
else
    echo "This is a directory"
fi

回答5:

UPDATED: I was downvoted so I decided to re-write my answer, thanks for the feedback.

Using the "file" command may be useful for this:

#!/bin/bash
check_file(){

if [ -z "${1}" ] ;then
 echo "Please input something"
 return;
fi

f="${1}"
result="$(file $f)"
if [[ $result == *"cannot open"* ]] ;then
        echo "NO FILE FOUND ($result) ";
elif [[ $result == *"directory"* ]] ;then
        echo "DIRECTORY FOUND ($result) ";
else
        echo "FILE FOUND ($result) ";
fi

}

check_file ${1}

Output examples :

$ ./f.bash login
DIRECTORY FOUND (login: directory) 
$ ./f.bash ldasdas
NO FILE FOUND (ldasdas: cannot open `ldasdas' (No such file or  directory)) 
$ ./f.bash evil.php 
FILE FOUND (evil.php: PHP script, ASCII text) 

FYI: the answers above work but you can use -s to help in weird situations by checking for a valid file first:

#!/bin/bash

check_file(){
    local file="${1}"
    [[ -s "${file}" ]] || { echo "is not valid"; return; } 
    [[ -d "${file}" ]] && { echo "is a directory"; return; }
    [[ -f "${file}" ]] && { echo "is a file"; return; }
}

check_file ${1}

回答6:

#!/bin/bash                                                                                               
echo "Please Enter a file name :"                                                                          
read filename                                                                                             
if test -f $filename                                                                                      
then                                                                                                      
        echo "this is a file"                                                                             
else                                                                                                      
        echo "this is not a file"                                                                         
fi