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How can I create a /dev/null-like “blackhole” directory?

How do I point certain directory to /dev/null?Can I prevent a file from being created?How can I trick Plex Media Server into writing logs to a black hole?Is it possible to trick a program into thinking it write successfully but don't write anything to disk?Is there a kind of '/dev/null' to fake output file path?Monitor directory and if a file is requested then rsync on demandCreate a recursive diff directory. Copy reference and diff. Recreate original directoryHow to strip directory structure with command line (or script)Can two files in a directory be on different filesystemsHow can there be a directory named `~`?How to output files to another directory (Poppler - pdftotext)Should I use single or double angle brackets to redirect to /dev/null?Is it safe to store persistent data into /var/app_name/Finding modified files in realtime?

.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty{ margin-bottom:0;
}

80

21

I would like to create a "/dev/null" directory (or a "blackhole" directory) such that any files written to it are not really written, but just disappear.

I have an application that writes out large temporary files to a directory. I have no control over the name of the files and I don't really care about the content of these files. I could write a script that periodically clobbers these files, but the files are written out very quickly and fill my disk. I'm looking for something cleverer. I want the application to "think" that it is writing out these files, when in fact, the writes are just being discarded at the other end.

Also see this old related thread.

filesystems directory io-redirection

share|improve this question

edited Mar 16 '11 at 21:45

Gilles

574k140140 gold badges11841184 silver badges16961696 bronze badges

asked Mar 16 '11 at 8:57

dogbanedogbane

15.6k1010 gold badges6565 silver badges5858 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  It sounds like FUSE might be an option: kerneltrap.org/mailarchive/linux-kernel/2008/2/15/868564/thread
  
  – Stefan Lasiewski
  Mar 16 '11 at 20:32
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  i just asked myself the same question, and used the same name for the directory i failed to create.
  
  – ixtmixilix
  Mar 3 '13 at 6:56
  

  
  
  
  

add a comment | 

80

21

I would like to create a "/dev/null" directory (or a "blackhole" directory) such that any files written to it are not really written, but just disappear.

I have an application that writes out large temporary files to a directory. I have no control over the name of the files and I don't really care about the content of these files. I could write a script that periodically clobbers these files, but the files are written out very quickly and fill my disk. I'm looking for something cleverer. I want the application to "think" that it is writing out these files, when in fact, the writes are just being discarded at the other end.

Also see this old related thread.

filesystems directory io-redirection

share|improve this question

edited Mar 16 '11 at 21:45

Gilles

574k140140 gold badges11841184 silver badges16961696 bronze badges

asked Mar 16 '11 at 8:57

dogbanedogbane

15.6k1010 gold badges6565 silver badges5858 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  It sounds like FUSE might be an option: kerneltrap.org/mailarchive/linux-kernel/2008/2/15/868564/thread
  
  – Stefan Lasiewski
  Mar 16 '11 at 20:32
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  i just asked myself the same question, and used the same name for the directory i failed to create.
  
  – ixtmixilix
  Mar 3 '13 at 6:56
  

  
  
  
  

add a comment | 

I would like to create a "/dev/null" directory (or a "blackhole" directory) such that any files written to it are not really written, but just disappear.

I have an application that writes out large temporary files to a directory. I have no control over the name of the files and I don't really care about the content of these files. I could write a script that periodically clobbers these files, but the files are written out very quickly and fill my disk. I'm looking for something cleverer. I want the application to "think" that it is writing out these files, when in fact, the writes are just being discarded at the other end.

Also see this old related thread.

filesystems directory io-redirection

share|improve this question

edited Mar 16 '11 at 21:45

Gilles

574k140140 gold badges11841184 silver badges16961696 bronze badges

asked Mar 16 '11 at 8:57

dogbanedogbane

15.6k1010 gold badges6565 silver badges5858 bronze badges

share|improve this question

edited Mar 16 '11 at 21:45

Gilles

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asked Mar 16 '11 at 8:57

dogbanedogbane

15.6k1010 gold badges6565 silver badges5858 bronze badges

share|improve this question

edited Mar 16 '11 at 21:45

Gilles

574k140140 gold badges11841184 silver badges16961696 bronze badges

asked Mar 16 '11 at 8:57

dogbanedogbane

15.6k1010 gold badges6565 silver badges5858 bronze badges

edited Mar 16 '11 at 21:45

Gilles

574k140140 gold badges11841184 silver badges16961696 bronze badges

edited Mar 16 '11 at 21:45

Gilles

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asked Mar 16 '11 at 8:57

dogbanedogbane

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asked Mar 16 '11 at 8:57

dogbanedogbane

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6 Answers
6

active

oldest

votes

48

This isn't supported out-of-the-box on any unix I know, but you can do pretty much anything with FUSE. There's at least one implementation of nullfs¹, a filesystem where every file exists and behaves like /dev/null (this isn't the only implementation I've ever seen).

¹
_{Not to be confused with the *BSD nullfs, which is analogous to bindfs.}

share|improve this answer

answered Mar 16 '11 at 21:45

GillesGilles

574k140140 gold badges11841184 silver badges16961696 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Fantastic - I've used this as part of an answer on SO
  
  – Phil Lello
  May 5 '11 at 21:52
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  a note to people who end up with compile errors on that program: g++ -Wall -o nullfs nullfs.c++ `pkg-config fuse --cflags --libs` worked for me.
  
  – ixtmixilix
  Mar 3 '13 at 7:11
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Can you point me to other implementations? Because I can't find any
  
  – Freedo
  Aug 2 at 4:50
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Freedo I suspect many people have done it as a learning exercise and let it go unmaintained. They might not be on the web anymore.
  
  – Gilles
  Aug 2 at 6:07
  

  
  
  
  

add a comment | 

7

Another approach would be a LD_PRELOAD wrapper; basically a small shared library which is loaded before libc.so, and intercepts calls to "open" with something that checks the prospective file path and substitutes "/dev/null" if it would be in the target directory.

This has the advantage of being
(a) entirely in user-space - no kernel hacking required; and
(b) only affecting the single errant application.

A simple example is at http://www.noah.org/wiki/LD_PRELOAD_notes, but in your case you will want to intercept the "open" & "creat" system calls.

share|improve this answer

answered Apr 21 '13 at 1:29

Martin KealeyMartin Kealey

9111 silver badge22 bronze badges

• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  ...assuming the application does system calls via libc, not directly via int 0x80/syscall/sysenter/whatever else.
  
  – Ruslan
  Feb 7 '16 at 18:44
  

  
  
  
  

add a comment | 

1

If the program is so stupid to not let you switch those logs off, may be it also doesn't check for errors after opening a log file? I'd try mounting some dummy read-only file system (e.g. using mount -o loop.)

share|improve this answer

answered Mar 16 '11 at 9:56

alexalex

4,54944 gold badges2020 silver badges2929 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  this approach doesn't work unfortunately. The application dies if it can't write to this file.
  
  – dogbane
  Mar 16 '11 at 12:22
  

  
  
  
  

add a comment | 

1

You say that removing the files periodically with a script isn't fast enough. Could you live with a trigger that deletes a temporary file any time your application finishes writing and closes it? If so, you might make use of the "inotify" API.

(See http://en.wikipedia.org/wiki/Inotify and https://github.com/rvoicilas/inotify-tools/wiki/)

share|improve this answer

answered Mar 16 '11 at 20:17

Elliot NelsonElliot Nelson

11144 bronze badges

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  On many systems, deleting a file that a process has open removes its directory entry, but the file itself stays on disk until it is closed by the last process using it. Processes might write files and then seek to the beginning and read them back, and so the OS can't just throw the data away.
  
  – interfect
  Apr 18 '17 at 21:58
  

  
  
  
  

add a comment | 

0

i have created a kernel module based on the ramfs example in the linux kernel,
it is basically a blackhole filesystem called nullfsvfs. The FUSE system implementation needs to copy data from user to kernelspace and is quite slow, compared to a straight implementation as kernel module. See:

https://github.com/abbbi/nullfsvfs

share|improve this answer

answered 3 hours ago

michaelmichael

1

New contributor

michael is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

add a comment | 

-8

Just symlink that directory to /dev/null

rm -rf ~/.logs

ln -s /dev/null ~/.logs

/dev/null, doesn't have to be a directory. If the program tries writing to ~/.logs/log1.dump, it still goes right into /dev/null.

I do this for Google Chrome's cache because after a while it gets so big that Chrome will take minutes to start.

share|improve this answer

answered Mar 16 '11 at 12:54

jonescbjonescb

1,60111 gold badge1212 silver badges2020 bronze badges

• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  This wouldn't work because symlinks are files, not directories. Trying echo hello > ~/.logs/log1.dump gives ~/.logs/log1.dump: Not a directory. However, echo hello > ~/.logs works because .logs is a file.
  
  – dogbane
  Mar 16 '11 at 13:25
  
  
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  You must be kidding us. $ ln -s /dev/null dev-null; touch dev-null/zzz gives me touch: cannot touch 'dev-null/zzz': Not a directory
  
  – alex
  Mar 16 '11 at 13:28
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Like I said, it works for Chrome. It prevents it from writing into the cache. If it causes the asker's program to crash, then obviously it doesn't check if file pointers are NULL.
  
  – jonescb
  Mar 16 '11 at 13:54
  

  
  
  
  


• 
  
  
  

  
  6
  

  
  
  
  
  
  

  
  
  It probably means that Chrome skips writing if there is an error opening the file. You could achieve the same effect by removing write permission from the dump file or the directory its writing in.
  
  – KeithB
  Mar 16 '11 at 14:04
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  True, changing the permissions of the directory would probably make more sense.
  
  – jonescb
  Mar 16 '11 at 14:53
  

  
  
  
  

add a comment | 

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48

This isn't supported out-of-the-box on any unix I know, but you can do pretty much anything with FUSE. There's at least one implementation of nullfs¹, a filesystem where every file exists and behaves like /dev/null (this isn't the only implementation I've ever seen).

¹
_{Not to be confused with the *BSD nullfs, which is analogous to bindfs.}

share|improve this answer

answered Mar 16 '11 at 21:45

GillesGilles

574k140140 gold badges11841184 silver badges16961696 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Fantastic - I've used this as part of an answer on SO
  
  – Phil Lello
  May 5 '11 at 21:52
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  a note to people who end up with compile errors on that program: g++ -Wall -o nullfs nullfs.c++ `pkg-config fuse --cflags --libs` worked for me.
  
  – ixtmixilix
  Mar 3 '13 at 7:11
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Can you point me to other implementations? Because I can't find any
  
  – Freedo
  Aug 2 at 4:50
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Freedo I suspect many people have done it as a learning exercise and let it go unmaintained. They might not be on the web anymore.
  
  – Gilles
  Aug 2 at 6:07
  

  
  
  
  

add a comment | 

48

This isn't supported out-of-the-box on any unix I know, but you can do pretty much anything with FUSE. There's at least one implementation of nullfs¹, a filesystem where every file exists and behaves like /dev/null (this isn't the only implementation I've ever seen).

¹
_{Not to be confused with the *BSD nullfs, which is analogous to bindfs.}

share|improve this answer

answered Mar 16 '11 at 21:45

GillesGilles

574k140140 gold badges11841184 silver badges16961696 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Fantastic - I've used this as part of an answer on SO
  
  – Phil Lello
  May 5 '11 at 21:52
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  a note to people who end up with compile errors on that program: g++ -Wall -o nullfs nullfs.c++ `pkg-config fuse --cflags --libs` worked for me.
  
  – ixtmixilix
  Mar 3 '13 at 7:11
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Can you point me to other implementations? Because I can't find any
  
  – Freedo
  Aug 2 at 4:50
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Freedo I suspect many people have done it as a learning exercise and let it go unmaintained. They might not be on the web anymore.
  
  – Gilles
  Aug 2 at 6:07
  

  
  
  
  

add a comment | 

This isn't supported out-of-the-box on any unix I know, but you can do pretty much anything with FUSE. There's at least one implementation of nullfs¹, a filesystem where every file exists and behaves like /dev/null (this isn't the only implementation I've ever seen).

¹
_{Not to be confused with the *BSD nullfs, which is analogous to bindfs.}

share|improve this answer

answered Mar 16 '11 at 21:45

GillesGilles

574k140140 gold badges11841184 silver badges16961696 bronze badges

share|improve this answer

answered Mar 16 '11 at 21:45

GillesGilles

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answered Mar 16 '11 at 21:45

GillesGilles

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answered Mar 16 '11 at 21:45

GillesGilles

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7

Another approach would be a LD_PRELOAD wrapper; basically a small shared library which is loaded before libc.so, and intercepts calls to "open" with something that checks the prospective file path and substitutes "/dev/null" if it would be in the target directory.

This has the advantage of being
(a) entirely in user-space - no kernel hacking required; and
(b) only affecting the single errant application.

A simple example is at http://www.noah.org/wiki/LD_PRELOAD_notes, but in your case you will want to intercept the "open" & "creat" system calls.

share|improve this answer

answered Apr 21 '13 at 1:29

Martin KealeyMartin Kealey

9111 silver badge22 bronze badges

• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  ...assuming the application does system calls via libc, not directly via int 0x80/syscall/sysenter/whatever else.
  
  – Ruslan
  Feb 7 '16 at 18:44
  

  
  
  
  

add a comment | 

7

Another approach would be a LD_PRELOAD wrapper; basically a small shared library which is loaded before libc.so, and intercepts calls to "open" with something that checks the prospective file path and substitutes "/dev/null" if it would be in the target directory.

This has the advantage of being
(a) entirely in user-space - no kernel hacking required; and
(b) only affecting the single errant application.

A simple example is at http://www.noah.org/wiki/LD_PRELOAD_notes, but in your case you will want to intercept the "open" & "creat" system calls.

share|improve this answer

answered Apr 21 '13 at 1:29

Martin KealeyMartin Kealey

9111 silver badge22 bronze badges

• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  ...assuming the application does system calls via libc, not directly via int 0x80/syscall/sysenter/whatever else.
  
  – Ruslan
  Feb 7 '16 at 18:44
  

  
  
  
  

add a comment | 

Another approach would be a LD_PRELOAD wrapper; basically a small shared library which is loaded before libc.so, and intercepts calls to "open" with something that checks the prospective file path and substitutes "/dev/null" if it would be in the target directory.

This has the advantage of being
(a) entirely in user-space - no kernel hacking required; and
(b) only affecting the single errant application.

A simple example is at http://www.noah.org/wiki/LD_PRELOAD_notes, but in your case you will want to intercept the "open" & "creat" system calls.

share|improve this answer

answered Apr 21 '13 at 1:29

Martin KealeyMartin Kealey

9111 silver badge22 bronze badges

share|improve this answer

answered Apr 21 '13 at 1:29

Martin KealeyMartin Kealey

9111 silver badge22 bronze badges

answered Apr 21 '13 at 1:29

Martin KealeyMartin Kealey

9111 silver badge22 bronze badges

answered Apr 21 '13 at 1:29

Martin KealeyMartin Kealey

9111 silver badge22 bronze badges

1

If the program is so stupid to not let you switch those logs off, may be it also doesn't check for errors after opening a log file? I'd try mounting some dummy read-only file system (e.g. using mount -o loop.)

share|improve this answer

answered Mar 16 '11 at 9:56

alexalex

4,54944 gold badges2020 silver badges2929 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  this approach doesn't work unfortunately. The application dies if it can't write to this file.
  
  – dogbane
  Mar 16 '11 at 12:22
  

  
  
  
  

add a comment | 

1

If the program is so stupid to not let you switch those logs off, may be it also doesn't check for errors after opening a log file? I'd try mounting some dummy read-only file system (e.g. using mount -o loop.)

share|improve this answer

answered Mar 16 '11 at 9:56

alexalex

4,54944 gold badges2020 silver badges2929 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  this approach doesn't work unfortunately. The application dies if it can't write to this file.
  
  – dogbane
  Mar 16 '11 at 12:22
  

  
  
  
  

add a comment | 

If the program is so stupid to not let you switch those logs off, may be it also doesn't check for errors after opening a log file? I'd try mounting some dummy read-only file system (e.g. using mount -o loop.)

share|improve this answer

answered Mar 16 '11 at 9:56

alexalex

4,54944 gold badges2020 silver badges2929 bronze badges

share|improve this answer

answered Mar 16 '11 at 9:56

alexalex

4,54944 gold badges2020 silver badges2929 bronze badges

answered Mar 16 '11 at 9:56

alexalex

4,54944 gold badges2020 silver badges2929 bronze badges

answered Mar 16 '11 at 9:56

alexalex

4,54944 gold badges2020 silver badges2929 bronze badges

1

You say that removing the files periodically with a script isn't fast enough. Could you live with a trigger that deletes a temporary file any time your application finishes writing and closes it? If so, you might make use of the "inotify" API.

(See http://en.wikipedia.org/wiki/Inotify and https://github.com/rvoicilas/inotify-tools/wiki/)

share|improve this answer

answered Mar 16 '11 at 20:17

Elliot NelsonElliot Nelson

11144 bronze badges

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  On many systems, deleting a file that a process has open removes its directory entry, but the file itself stays on disk until it is closed by the last process using it. Processes might write files and then seek to the beginning and read them back, and so the OS can't just throw the data away.
  
  – interfect
  Apr 18 '17 at 21:58
  

  
  
  
  

add a comment | 

1

You say that removing the files periodically with a script isn't fast enough. Could you live with a trigger that deletes a temporary file any time your application finishes writing and closes it? If so, you might make use of the "inotify" API.

(See http://en.wikipedia.org/wiki/Inotify and https://github.com/rvoicilas/inotify-tools/wiki/)

share|improve this answer

answered Mar 16 '11 at 20:17

Elliot NelsonElliot Nelson

11144 bronze badges

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  On many systems, deleting a file that a process has open removes its directory entry, but the file itself stays on disk until it is closed by the last process using it. Processes might write files and then seek to the beginning and read them back, and so the OS can't just throw the data away.
  
  – interfect
  Apr 18 '17 at 21:58
  

  
  
  
  

add a comment | 

You say that removing the files periodically with a script isn't fast enough. Could you live with a trigger that deletes a temporary file any time your application finishes writing and closes it? If so, you might make use of the "inotify" API.

(See http://en.wikipedia.org/wiki/Inotify and https://github.com/rvoicilas/inotify-tools/wiki/)

share|improve this answer

answered Mar 16 '11 at 20:17

Elliot NelsonElliot Nelson

11144 bronze badges

share|improve this answer

answered Mar 16 '11 at 20:17

Elliot NelsonElliot Nelson

11144 bronze badges

answered Mar 16 '11 at 20:17

Elliot NelsonElliot Nelson

11144 bronze badges

answered Mar 16 '11 at 20:17

Elliot NelsonElliot Nelson

11144 bronze badges

0

i have created a kernel module based on the ramfs example in the linux kernel,
it is basically a blackhole filesystem called nullfsvfs. The FUSE system implementation needs to copy data from user to kernelspace and is quite slow, compared to a straight implementation as kernel module. See:

https://github.com/abbbi/nullfsvfs

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answered 3 hours ago

michaelmichael

1

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0

i have created a kernel module based on the ramfs example in the linux kernel,
it is basically a blackhole filesystem called nullfsvfs. The FUSE system implementation needs to copy data from user to kernelspace and is quite slow, compared to a straight implementation as kernel module. See:

https://github.com/abbbi/nullfsvfs

share|improve this answer

answered 3 hours ago

michaelmichael

1

New contributor

michael is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

add a comment | 

i have created a kernel module based on the ramfs example in the linux kernel,
it is basically a blackhole filesystem called nullfsvfs. The FUSE system implementation needs to copy data from user to kernelspace and is quite slow, compared to a straight implementation as kernel module. See:

https://github.com/abbbi/nullfsvfs

share|improve this answer

answered 3 hours ago

michaelmichael

1

New contributor

michael is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

share|improve this answer

answered 3 hours ago

michaelmichael

1

New contributor

michael is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

answered 3 hours ago

michaelmichael

1

New contributor

michael is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

answered 3 hours ago

michaelmichael

1

-8

Just symlink that directory to /dev/null

rm -rf ~/.logs

ln -s /dev/null ~/.logs

/dev/null, doesn't have to be a directory. If the program tries writing to ~/.logs/log1.dump, it still goes right into /dev/null.

I do this for Google Chrome's cache because after a while it gets so big that Chrome will take minutes to start.

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answered Mar 16 '11 at 12:54

jonescbjonescb

1,60111 gold badge1212 silver badges2020 bronze badges

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  This wouldn't work because symlinks are files, not directories. Trying echo hello > ~/.logs/log1.dump gives ~/.logs/log1.dump: Not a directory. However, echo hello > ~/.logs works because .logs is a file.
  
  – dogbane
  Mar 16 '11 at 13:25
  
  
  

  
  
  
  


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  You must be kidding us. $ ln -s /dev/null dev-null; touch dev-null/zzz gives me touch: cannot touch 'dev-null/zzz': Not a directory
  
  – alex
  Mar 16 '11 at 13:28
  

  
  
  
  


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  Like I said, it works for Chrome. It prevents it from writing into the cache. If it causes the asker's program to crash, then obviously it doesn't check if file pointers are NULL.
  
  – jonescb
  Mar 16 '11 at 13:54
  

  
  
  
  


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  It probably means that Chrome skips writing if there is an error opening the file. You could achieve the same effect by removing write permission from the dump file or the directory its writing in.
  
  – KeithB
  Mar 16 '11 at 14:04
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  True, changing the permissions of the directory would probably make more sense.
  
  – jonescb
  Mar 16 '11 at 14:53
  

  
  
  
  

add a comment | 

-8

Just symlink that directory to /dev/null

rm -rf ~/.logs

ln -s /dev/null ~/.logs

/dev/null, doesn't have to be a directory. If the program tries writing to ~/.logs/log1.dump, it still goes right into /dev/null.

I do this for Google Chrome's cache because after a while it gets so big that Chrome will take minutes to start.

share|improve this answer

answered Mar 16 '11 at 12:54

jonescbjonescb

1,60111 gold badge1212 silver badges2020 bronze badges

• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  This wouldn't work because symlinks are files, not directories. Trying echo hello > ~/.logs/log1.dump gives ~/.logs/log1.dump: Not a directory. However, echo hello > ~/.logs works because .logs is a file.
  
  – dogbane
  Mar 16 '11 at 13:25
  
  
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  You must be kidding us. $ ln -s /dev/null dev-null; touch dev-null/zzz gives me touch: cannot touch 'dev-null/zzz': Not a directory
  
  – alex
  Mar 16 '11 at 13:28
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Like I said, it works for Chrome. It prevents it from writing into the cache. If it causes the asker's program to crash, then obviously it doesn't check if file pointers are NULL.
  
  – jonescb
  Mar 16 '11 at 13:54
  

  
  
  
  


• 
  
  
  

  
  6
  

  
  
  
  
  
  

  
  
  It probably means that Chrome skips writing if there is an error opening the file. You could achieve the same effect by removing write permission from the dump file or the directory its writing in.
  
  – KeithB
  Mar 16 '11 at 14:04
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  True, changing the permissions of the directory would probably make more sense.
  
  – jonescb
  Mar 16 '11 at 14:53
  

  
  
  
  

add a comment | 

Just symlink that directory to /dev/null

rm -rf ~/.logs

ln -s /dev/null ~/.logs

/dev/null, doesn't have to be a directory. If the program tries writing to ~/.logs/log1.dump, it still goes right into /dev/null.

I do this for Google Chrome's cache because after a while it gets so big that Chrome will take minutes to start.

share|improve this answer

answered Mar 16 '11 at 12:54

jonescbjonescb

1,60111 gold badge1212 silver badges2020 bronze badges

rm -rf ~/.logs

ln -s /dev/null ~/.logs

share|improve this answer

answered Mar 16 '11 at 12:54

jonescbjonescb

1,60111 gold badge1212 silver badges2020 bronze badges

answered Mar 16 '11 at 12:54

jonescbjonescb

1,60111 gold badge1212 silver badges2020 bronze badges

answered Mar 16 '11 at 12:54

jonescbjonescb

1,60111 gold badge1212 silver badges2020 bronze badges