2

The bash script does many things. However, at beginning it should start if the input passed to the script is a directory path. For example, right way of telling directory path is "/var/lib/test", and incorrect way is "/var/%%^?/test".

where test is a directory and not a file.

The directory path can contain characters. [A-Za-z0-9/_-]

My script is as below - 

#!/bin/bash
dirPath="/var/lib/test"
if [[ ! ${dirPath} =~ "^/[A-Za-z0-9/_-]+$" ]]; then
    echo "Success"
else
    echo "Failure"
fi

Here, dirPath can have any path provided from another script.

please let me know the error here.

Improve this question
12
  • I don't exactly understand the question. So the above script returns Success. Is that expected? Can you give some examples of when it should return Failure and Success? Commented Sep 28, 2018 at 11:45
  • Is the issue the characters in the path? /var/%%^?/test is a valid pathname on Unix. Would it be enough to test whether the given path denotes an existing directory? Commented Sep 28, 2018 at 11:45
  • The script should test if the given directory path is valid or not. Valid directory path includes characters - [A-Za-z0-9_-/] Commented Sep 28, 2018 at 11:50
  • 1
    @Goro Inside [...] in a regular expression, there are no delimiters. Even backslashes would be taken as literal backslashes. Commented Sep 28, 2018 at 12:23
  • 1
    @Goro, Bash's =~ doesn't take slashes to delimit the regex Commented Sep 28, 2018 at 12:24

4 Answers 4

Reset to default
4 
if [[ ! ${dirPath} =~ "^/[A-Za-z0-9/_-]+$" ]]; then
    echo "Success"

This will test $dirPath against the literal string ^/[A-Za-z0-9/_-]+$, and invert the result. In other words, it will print Success when $dirPath is anything other than that literal string. This is because quoted characters in a regex lose their special meaning in current versions of Bash, and of course the ! works to invert the test.

If you want to test that variable against the actual regex, it's easiest to put the regex in a variable first, and leave it unquoted (using a variable may not be strictly necessary, but avoids some parsing issues with complex regexes):

dirPath="/var/lib/test"
re='^/[A-Za-z0-9/_-]+$'
if [[ ${dirPath} =~ $re ]]; then
    echo "'$dirPath' starts with a slash, and is composed of alphanumerics, hyphens, underscores and slashes only"
else
    echo "'$dirPath' is of a forbidden format"
fi

Of course, if you want to test if that path is an existing directory, then you'd use -d:

if [[ -d $dirPath ]]; then
    echo "'$dirPath' exists and is a directory
fi
Improve this answer
0
4

Remove the quotes from the regex:

[[ ! "${dirPath}" =~ ^/[A-Za-z0-9/_-]+$ ]]

Quoting the regex forces string matching since Bash 3.2.

Compare this question on Stackoverflow.

Note: while this fixes your script, it does not properly check if the path is a correct directory path. Refer to @Kusalanandas answer how to do a proper check.

Improve this answer
0
2

This answer focuses on the first part of the question which (currently) reads:

However, at beginning it should start if the input passed to the script is a directory path.

The rest of the question is an attempt at doing this by matching a particular regular expression against a pathname to try to figure out whether it's a valid directory pathname.

A script should not generally impose an arbitrary naming scheme on the user's directories or files without reason. The pathname /var/%%^?/test is perfectly valid on a system where there exists a directory called %%^? under /var and where this directory contains a subdirectory called test.

What your script is really concerned about is whether it's given a pathname to an existing directory. Whatever the directory path is is less important.

This may be done with

#!/bin/bash

dirPath=$1

if [ ! -d "$dirPath" ]; then
    printf '"%s" is not a valid directory path\n' "$dirPath" >&2
    exit 1
fi

After this if-statement, you know that "$dirPath" is the path to an existing directory. The pathname to the directory is (in the above code) taken from the first command line argument.

Improve this answer
0
0

to check if its file or dir you don't need regex - use:

if [ -d "${testpath}" ] ; then
    echo "$testpath is a directory";
Improve this answer

You must log in to answer this question.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.