Tjyylli

Can I cast a spell through the Invoke Duplicity clone while inside a Forcecage?

Was it really inappropriate to write a pull request for the company I interviewed with?

It doesn't matter the side you see it

When to use mean vs median

Four buttons on a table

Practical reasons to have both a large police force and bounty hunting network?

If there are any 3nion, 5nion, 7nion, 9nion, 10nion, etc.

Sometimes a banana is just a banana

How to merge row in the first column in LaTeX

Do AL rules let me pick different starting equipment?

Difference between 'stomach' and 'uterus'

PTIJ: Aharon, King of Egypt

How to fix my table, centering of columns

Formatting a table to look nice

Reason why dimensional travelling would be restricted

Why do phishing e-mails use faked e-mail addresses instead of the real one?

Is there a frame of reference in which I was born before I was conceived?

I can't die. Who am I?

Can an earth elemental drown/bury its opponent underground using earth glide?

Did Amazon pay $0 in taxes last year?

Where is the fallacy here?

Why are special aircraft used for the carriers in the United States Navy?

Meaning of word ягоза

What is the minimum amount of skill points per HD?

How can I work with the real file behind a symlink?

Problem restoring from tar backup: why are there /dev/disk/by-id/ symlinks and how can I avoid them?Find strings that appear consecutively in a fileFind a file in the CWD or any of its parentsShell script bash: Moving file iterate based on monthHow to create destination directory structure dynamically when using mv with wildcards in bash?Symlink two real directories with files in bothFile Operations Using Symlink Source/Destinationcan bash “source” a custom-interpreter shell?Strange Undeletable FolderCreating a Windows application that has to call bash scripts and Python scripts that use Linux-based modules?

0

I have a file and a symlink:

file: ~/${USER_HOME}/blabla/.cheatsheet

symlink: ~/.cheatsheet (is linked to file above)

Now in my script I do some operations with the file, e.g. add a line and sort the file alphabetically and move it:

addOneCommand() {

  file"=~/.cheatsheet"

  # add it to the file

  echo "${cmd}" >> "${file}"

  # sort file instantly

  cat "${file}" | sort > "${file}".tmp

  mv "${file}".tmp "${file}"

}

But the real file behind the symlink doesn't get affected by the script (e.g. not sorted alphabetically).
What can I do to work with "symlinked files" in bash scripts?

Thanks.

linux bash symbolic-link

share|improve this question

asked yesterday

m1wellm1well

155

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Note: file"=~/.cheatsheet" is not going to work.
  
  – Kamil Maciorowski
  yesterday
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  You may find stackoverflow.com/questions/7665/… or stackoverflow.com/questions/29789204/… or unix.stackexchange.com/questions/167631/… or serverfault.com/questions/76042/… of interest.
  
  – Jeff Zeitlin
  yesterday
  

  
  
  
  

add a comment | 

0

I have a file and a symlink:

file: ~/${USER_HOME}/blabla/.cheatsheet

symlink: ~/.cheatsheet (is linked to file above)

Now in my script I do some operations with the file, e.g. add a line and sort the file alphabetically and move it:

addOneCommand() {

  file"=~/.cheatsheet"

  # add it to the file

  echo "${cmd}" >> "${file}"

  # sort file instantly

  cat "${file}" | sort > "${file}".tmp

  mv "${file}".tmp "${file}"

}

But the real file behind the symlink doesn't get affected by the script (e.g. not sorted alphabetically).
What can I do to work with "symlinked files" in bash scripts?

Thanks.

linux bash symbolic-link

share|improve this question

asked yesterday

m1wellm1well

155

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Note: file"=~/.cheatsheet" is not going to work.
  
  – Kamil Maciorowski
  yesterday
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  You may find stackoverflow.com/questions/7665/… or stackoverflow.com/questions/29789204/… or unix.stackexchange.com/questions/167631/… or serverfault.com/questions/76042/… of interest.
  
  – Jeff Zeitlin
  yesterday
  

  
  
  
  

add a comment | 

I have a file and a symlink:

file: ~/${USER_HOME}/blabla/.cheatsheet

symlink: ~/.cheatsheet (is linked to file above)

Now in my script I do some operations with the file, e.g. add a line and sort the file alphabetically and move it:

addOneCommand() {

  file"=~/.cheatsheet"

  # add it to the file

  echo "${cmd}" >> "${file}"

  # sort file instantly

  cat "${file}" | sort > "${file}".tmp

  mv "${file}".tmp "${file}"

}

But the real file behind the symlink doesn't get affected by the script (e.g. not sorted alphabetically).
What can I do to work with "symlinked files" in bash scripts?

Thanks.

linux bash symbolic-link

share|improve this question

asked yesterday

m1wellm1well

155

file: ~/${USER_HOME}/blabla/.cheatsheet

symlink: ~/.cheatsheet (is linked to file above)

addOneCommand() {

  file"=~/.cheatsheet"

  # add it to the file

  echo "${cmd}" >> "${file}"

  # sort file instantly

  cat "${file}" | sort > "${file}".tmp

  mv "${file}".tmp "${file}"

}

share|improve this question

asked yesterday

m1wellm1well

155

share|improve this question

asked yesterday

m1wellm1well

155

asked yesterday

m1wellm1well

155

asked yesterday

m1wellm1well

155

3 Answers
3

active

oldest

votes

0

The point is, that you create a new file ${file}.tmp, that is now not a symlink, then rename.

You might try

cat "${file}".tmp >"${file}"

rm "${file}".tmp

instead of

mv "${file}".tmp "${file}"

If you don't mind the race condition.

P.S.: If I understand your intention correctly, you might want sort -u instead of plain sort

share|improve this answer

answered yesterday

Eugen RieckEugen Rieck

11k22429

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  ah ok - that's it - thanks :)
  
  – m1well
  yesterday
  

  
  
  
  

add a comment | 

0

Your issue is that you're using mv, which will replace the symlink.

You can use a number of other approaches (see Eugen Rieck's answer for one), but fundamentally, you need to reuse the symlink, not replace it.

sponge is a good tool that will also allow you to remove handling of the *.tmp file as well:

With a file a, that is symlinked from b:

$ echo -e "3n1n2" > a

$ ln -s a b

$ ls -l

total 1

-rw-r--r-- 1 attie attie 6 Mar  5 15:44 a

lrwxrwxrwx 1 attie attie 1 Mar  5 15:44 b -> a

You can sort and rewrite a via b, without affecting the symlink:

$ cat b | sort | sponge b

$ ls -l

total 1

-rw-r--r-- 1 attie attie 6 Mar  5 15:44 a

lrwxrwxrwx 1 attie attie 1 Mar  5 15:44 b -> a

$ cat b

1

2

3

share|improve this answer

answered yesterday

AttieAttie

11.7k32845

add a comment | 

0

You can find the real file behind the symlink using the readlink or realpath commands.

share|improve this answer

answered yesterday

xenoidxenoid

3,7683719

add a comment | 

Your Answer

StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "3"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});

function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});


}
});

draft saved

draft discarded

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Sign up using Google

Sign up using Facebook

Sign up using Email and Password

Post as a guest

Name

Email

Required, but never shown

StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fsuperuser.com%2fquestions%2f1411491%2fhow-can-i-work-with-the-real-file-behind-a-symlink%23new-answer', 'question_page');
}
);

Post as a guest

Name

Email

Required, but never shown

0

The point is, that you create a new file ${file}.tmp, that is now not a symlink, then rename.

You might try

cat "${file}".tmp >"${file}"

rm "${file}".tmp

instead of

mv "${file}".tmp "${file}"

If you don't mind the race condition.

P.S.: If I understand your intention correctly, you might want sort -u instead of plain sort

share|improve this answer

answered yesterday

Eugen RieckEugen Rieck

11k22429

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  ah ok - that's it - thanks :)
  
  – m1well
  yesterday
  

  
  
  
  

add a comment | 

0

The point is, that you create a new file ${file}.tmp, that is now not a symlink, then rename.

You might try

cat "${file}".tmp >"${file}"

rm "${file}".tmp

instead of

mv "${file}".tmp "${file}"

If you don't mind the race condition.

P.S.: If I understand your intention correctly, you might want sort -u instead of plain sort

share|improve this answer

answered yesterday

Eugen RieckEugen Rieck

11k22429

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  ah ok - that's it - thanks :)
  
  – m1well
  yesterday
  

  
  
  
  

add a comment | 

The point is, that you create a new file ${file}.tmp, that is now not a symlink, then rename.

You might try

cat "${file}".tmp >"${file}"

rm "${file}".tmp

instead of

mv "${file}".tmp "${file}"

If you don't mind the race condition.

P.S.: If I understand your intention correctly, you might want sort -u instead of plain sort

share|improve this answer

answered yesterday

Eugen RieckEugen Rieck

11k22429

cat "${file}".tmp >"${file}"

rm "${file}".tmp

mv "${file}".tmp "${file}"

share|improve this answer

answered yesterday

Eugen RieckEugen Rieck

11k22429

answered yesterday

Eugen RieckEugen Rieck

11k22429

answered yesterday

Eugen RieckEugen Rieck

11k22429

0

Your issue is that you're using mv, which will replace the symlink.

You can use a number of other approaches (see Eugen Rieck's answer for one), but fundamentally, you need to reuse the symlink, not replace it.

sponge is a good tool that will also allow you to remove handling of the *.tmp file as well:

With a file a, that is symlinked from b:

$ echo -e "3n1n2" > a

$ ln -s a b

$ ls -l

total 1

-rw-r--r-- 1 attie attie 6 Mar  5 15:44 a

lrwxrwxrwx 1 attie attie 1 Mar  5 15:44 b -> a

You can sort and rewrite a via b, without affecting the symlink:

$ cat b | sort | sponge b

$ ls -l

total 1

-rw-r--r-- 1 attie attie 6 Mar  5 15:44 a

lrwxrwxrwx 1 attie attie 1 Mar  5 15:44 b -> a

$ cat b

1

2

3

share|improve this answer

answered yesterday

AttieAttie

11.7k32845

add a comment | 

0

Your issue is that you're using mv, which will replace the symlink.

You can use a number of other approaches (see Eugen Rieck's answer for one), but fundamentally, you need to reuse the symlink, not replace it.

sponge is a good tool that will also allow you to remove handling of the *.tmp file as well:

With a file a, that is symlinked from b:

$ echo -e "3n1n2" > a

$ ln -s a b

$ ls -l

total 1

-rw-r--r-- 1 attie attie 6 Mar  5 15:44 a

lrwxrwxrwx 1 attie attie 1 Mar  5 15:44 b -> a

You can sort and rewrite a via b, without affecting the symlink:

$ cat b | sort | sponge b

$ ls -l

total 1

-rw-r--r-- 1 attie attie 6 Mar  5 15:44 a

lrwxrwxrwx 1 attie attie 1 Mar  5 15:44 b -> a

$ cat b

1

2

3

share|improve this answer

answered yesterday

AttieAttie

11.7k32845

add a comment | 

Your issue is that you're using mv, which will replace the symlink.

You can use a number of other approaches (see Eugen Rieck's answer for one), but fundamentally, you need to reuse the symlink, not replace it.

sponge is a good tool that will also allow you to remove handling of the *.tmp file as well:

With a file a, that is symlinked from b:

$ echo -e "3n1n2" > a

$ ln -s a b

$ ls -l

total 1

-rw-r--r-- 1 attie attie 6 Mar  5 15:44 a

lrwxrwxrwx 1 attie attie 1 Mar  5 15:44 b -> a

You can sort and rewrite a via b, without affecting the symlink:

$ cat b | sort | sponge b

$ ls -l

total 1

-rw-r--r-- 1 attie attie 6 Mar  5 15:44 a

lrwxrwxrwx 1 attie attie 1 Mar  5 15:44 b -> a

$ cat b

1

2

3

share|improve this answer

answered yesterday

AttieAttie

11.7k32845

$ echo -e "3n1n2" > a

$ ln -s a b

$ ls -l

total 1

-rw-r--r-- 1 attie attie 6 Mar  5 15:44 a

lrwxrwxrwx 1 attie attie 1 Mar  5 15:44 b -> a

$ cat b | sort | sponge b

$ ls -l

total 1

-rw-r--r-- 1 attie attie 6 Mar  5 15:44 a

lrwxrwxrwx 1 attie attie 1 Mar  5 15:44 b -> a

$ cat b

1

2

3

share|improve this answer

answered yesterday

AttieAttie

11.7k32845

answered yesterday

AttieAttie

11.7k32845

answered yesterday

AttieAttie

11.7k32845

0

You can find the real file behind the symlink using the readlink or realpath commands.

share|improve this answer

answered yesterday

xenoidxenoid

3,7683719

add a comment | 

0

You can find the real file behind the symlink using the readlink or realpath commands.

share|improve this answer

answered yesterday

xenoidxenoid

3,7683719

add a comment | 

You can find the real file behind the symlink using the readlink or realpath commands.

share|improve this answer

answered yesterday

xenoidxenoid

3,7683719

share|improve this answer

answered yesterday

xenoidxenoid

3,7683719

answered yesterday

xenoidxenoid

3,7683719

answered yesterday

xenoidxenoid

3,7683719