LinuxQuestions.org - [SOLVED] Problems passing a string to if statement

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Problems passing a string to if statement

I'm trying to have a script read a text file, line by line, and then back up the directories which will be listed in each line. Obviously, I need to make sure that these are actually directories. So something like this seems to be a simple way to do it:

Code:

#! /usr/bin/bash

#



FILE="testfile.txt"



while read line; do

    if [ -d "$line" ]; then

        echo "This IS a path! - $line"

        # backup script goes here

      else

        echo "This isn't a path: $line"

        # do nothing

    fi

done < $FILE

The problem is it doesn't work. testfile.txt contains a load of gibberish and two valid paths, but this script doesn't recognise any of the lines as valid. I know the last two lines *are* valid, though, because when I type the following directly into a shell, it works:

Code:

if [ -d /some/valid/path/copied/from/the/text/file ]; then echo "IT'S A PATH"; else echo "nope"; fi;

I'm assuming this is some elementary error in the way I'm passing the contents of $line into the if statement, but I don't know what I'm doing wrong!

Can you show me two or three lines from the textfile and say what kind of error the script produce?

Sure - this is testfile.txt (I started off thinking I'd use hashes to comment out lines I didn't want, but then realised it was safer to treat any line as junk unless it specifically tested positive as a folder):

Code:

## How to use:



Line 1 - something

Line 2's got a quote mark

Line 3 has "double quotes"

Line 4 has a /slash

Line 5 blah blah blah.

this isn't a comment

## this is a comment

normal line.

blank line below:



/valid/path/number/one

/valid/path/number/two

The script doesn't produce any errors, but every line it reads produces the "this isn't a path" output.

as in, this is the output:

Code:

This isn't a path: ## How to use:

This isn't a path:

This isn't a path: Line 1 - something

This isn't a path: Line 2's got a quote mark

This isn't a path: Line 3 has "double quotes"

This isn't a path: Line 4 has a /slash

This isn't a path: Line 5 blah blah blah.

This isn't a path: this isn't a comment

This isn't a path: ## this is a comment

This isn't a path: normal line.

This isn't a path: blank line below:

This isn't a path:

This isn't a path: /valid/path/number/one

This isn't a path: /valid/path/number/two

Just delete double quotes in test statement:

if [ -d $line ]; then

I tried that, but as the lines might contain spaces it gives me an error like this on virtually every line it reads -

Code:

readline_test.sh: line 9: [: too many arguments

... presumably it's expanding the string to something like

Code:

if [ -d ## How to use: ]; then

I've also tried

Code:

if [[ -d $line ]]; then

which doesn't throw any errors, but it does always go to the "this isn't a path" branch irrespective of whether $line is a path or not.

use [[ ]] definitely, as per your last comment.

It looks fine to me either way though, can you genuinely prove these paths DO exist? Just use "/etc" for example.

Are you sure those directories exist? I have just tried your script and it worked fine:

This isn't a path: ## How to use:
This isn't a path:
This isn't a path: Line 1 - something
This isn't a path: Line 2's got a quote mark
This isn't a path: Line 3 has "double quotes"
This isn't a path: Line 4 has a /slash
This isn't a path: Line 5 blah blah blah.
This isn't a path: this isn't a comment
This isn't a path: ## this is a comment
This isn't a path: normal line.
This isn't a path: blank line below:
This isn't a path:
This IS a path! - /tmp/test

If you are just testing that format makes sence as path, you can't use -d as it tests existence of directory

hmm, I must be going mad!

I've tried putting different paths in the text file:

Code:

[/tmp/temp] # cat testfile.txt

## How to use:



Line 1 - something

Line 2's got a quote mark

Line 3 has "double quotes"

Line 4 has a /slash

Line 5 blah blah blah.

this isn't a comment

## this is a comment

normal line.

blank line below:



/etc

/usr/bin

/tmp

[/tmp/temp] #

Output is:

Code:

This is not a path: ## How to use:

This is not a path:

This is not a path: Line 1 - something

This is not a path: Line 2's got a quote mark

This is not a path: Line 3 has "double quotes"

This is not a path: Line 4 has a /slash

This is not a path: Line 5 blah blah blah.

This is not a path: this isn't a comment

This is not a path: ## this is a comment

This is not a path: normal line.

This is not a path: blank line below:

This is not a path:

This is not a path: /etc

This is not a path: /usr/bin

This is not a path: /tmp

But (obviously) the last three do exist:

Code:

[/tmp/temp] # cd /etc

[/etc] # cd /usr/bin

[/usr/bin] # cd /tmp

[/tmp] #

(I've changed the echo statements slightly getting rid of exclamation marks and apostrophes in case they were causing any problems)

ok, is the file in unix format? Could there be a little ^M hiding at the end or something?

You're a genius. It wasn't, I've changed it to Unix format and it now works. Thank you! :)