What does mean linux

What does «. ./» mean in Linux shell? [duplicate]

I have a shell script that doesn’t execute with ./script.sh but it requires . ./script.sh to execute.

What is the difference between ./ and . ./ ? I am using the MSYS2 environment on Windows. Please note the space between the dots. I know what ../ , does and that doesn’t solve the issue, as I am in the same directory as my executable.

Here’s the output:

2 Answers 2

. is a source operator in Bash and multiple other POSIX shells:

It’s always safer to do . ./script instead of . script because . searches PATH by default and you can run into name collisions:

And because some shells do not search current directory be default:

The two are completely different, and can not be compared.

./ means the current directory.

. ./ means nothing like as it is, running will print the following error:

However, it needs to be broken down in two:

The . command is a shell built-in which is a synonym to the source command. It takes a file and not a directory as a parameter which is why you would get the error above.

A very command example that you might have seen is the following command:

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What does * mean in linux directory listing [closed]

Want to improve this question? Update the question so it’s on-topic for Stack Overflow.

Closed 4 years ago .

I’m looking at a flask app and when I perform

what does the * in dispatch.fcgi* mean

4 Answers 4

Quoting from man ls :

These are indicators appended to filenames according to their type

1. * for executable
2. / for directory
3. | for pipe

As mentioned in Ignacio Vazquez-Abrams’s answer, it means that the file is executable. A classifier is shown when -F is passed to ls via the command line or otherwise.

You might notice that each file with an * following its name is also a file with execute permissions set.

They are executable files, meaning the +x bit is set. Use ls —classify to get these indicators after file names.

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What does «. ./» mean in Linux shell? [duplicate]

I have a shell script that doesn’t execute with ./script.sh but it requires . ./script.sh to execute.

What is the difference between ./ and . ./ ? I am using the MSYS2 environment on Windows. Please note the space between the dots. I know what ../ , does and that doesn’t solve the issue, as I am in the same directory as my executable.

Here’s the output:

2 Answers 2

. is a source operator in Bash and multiple other POSIX shells:

It’s always safer to do . ./script instead of . script because . searches PATH by default and you can run into name collisions:

And because some shells do not search current directory be default:

The two are completely different, and can not be compared.

./ means the current directory.

. ./ means nothing like as it is, running will print the following error:

However, it needs to be broken down in two:

The . command is a shell built-in which is a synonym to the source command. It takes a file and not a directory as a parameter which is why you would get the error above.

A very command example that you might have seen is the following command:

Источник

What does ./ mean? [duplicate]

I’m having a hard time getting what ./ does.

In the Linux Essentials books, it asks me in an exercise to delete a file named -file . After googling, I found that I need to do rm ./-file but I don’t get why!

3 Answers 3

The . directory is the current directory. The directory .. is the upper level of that directory

In Linux, commands options are introduced by the — sign, i.e., ls -l , so if you want to make any reference to a file beginning with — such as -file , the command would think you are trying to specify an option. For example, if you want to remove it:

will complain because it’s trying to use the option file of the command rm . In this case you need to indicate where the file is. Being in the current directory, thus the . directory, you need to refer to that file as ./-file , meaning, in the directory . , the file -file . In this case the command rm won’t think that’s an option.

It can be done, also, using — .

To remove a file whose name starts with a ‘-‘, for example ‘-foo’, use one of these commands:

. is the current directory. So e.g. ls and ls . are synonymous. If you are in /etc the commands cat /etc/fstab/ , cat ./fstab and cat fstab do the same thing.

rm ./-file is used because rm parses everything starting with — as command line options and not file names. For example ls -l does not try to show file named -l , but ls ./-l and ls /some/directory/-l do.

If you type rm -file you will be passing a commandline option to rm not the name -file .

To delete -file pass rm the name in quotes rm «-file» or escape the — . rm \\-file . In either bash or zsh if you are unsure that a command is getting the proper filename use tab completion. Examples: type rm -fi TAB if the screen does not printout rm -file you know you did something wrong and should fix it before hitting return, another example rm «-fi TAB should printout rm «-file» .

As for ./ , / is just the separator between directories and filenames. «.» means present directory. «..» means the directory one up. So to delete the file foo in the present directory type rm ./foo ( rm foo is OK too ) to delete the file one directory up type rm ../foo to delete the file in the directory bar which is contained in the directory above type rm ../bar/foo .

In this case ./ is put in front of -file so that the — character is not the first thing that rm sees because that would make it think you are using some option.

If you know a bit of DOS, rm -file would correspond to rm /file in DOS.

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What does !$ mean?

I’m following through a tutorial and it mentions to run this command:

I’m not familiar with !$ . What does it mean?

3 Answers 3

Basically, it’s the last argument to the previous command.

!$ is the «end» of the previous command. Consider the following example: We start by looking for a word in a file:

if joe is in that userlist, we want to remove him from it. We can either fire up vi with that long directory tree as the argument, or as simply as vi !$ Which bash expands to:

(source; handy guide, by the way)

It’s worth nothing the distinction between this !$ token and the special shell variable $_ . Indeed, both expand to the last argument of the previous command. However, !$ is expanded during history expansion, while $_ is expanded during parameter expansion. One important consequence of this is that, when you use !$ , the expanded command is saved in your history.

For example, consider the keystrokes

echo Foo Enter echo !$ Jar Enter Up Enter ; and

echo Foo Enter echo $_ Jar Enter Up Enter .

(The only characters changed are the $! and $_ in the middle.)

In the former, when you press Up , the command line reads echo Foo Jar , so the last line written to stdout is Foo Jar .

In the latter, when you press Up , the command line reads echo $_ bar , but now $_ has a different value than it did previously—indeed, $_ is now Jar , so the last line written to stdout is Jar Jar .

Another consequence is that _ can be used in other parameter expansions, for example, the sequence of commands

prints isomorphism isosceles . But there’s no analogous » $ » expansion.

For more information about the phases of expansion in Bash, see the EXPANSION section of man 1 bash (this is called Shell Expansions in the online edition). The HISTORY EXPANSION section is separate.

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