Can you tell a 15kHz sine wave from a 15kHz sawtooth wave? A CD can't, because there are only three samples per crest and almost every teenager can easily hear 15kHz.
Even a teenager cannot tell the difference between a 15kHz sine wave and a 15kHz sawtooth wave. The first harmonic of a 15kHz sawtooth wave above the fundamental frequency is at 30kHz. Please don't tell me that you believe that any human can hear frequencies that high.
Please make standard-compliant shell-scripts, use #!/bin/sh
Something in freetard-land is standard? Oh please, do tell. Which standard? Who has to follow the standard? If no one has to follow it, then it's not a standard. Freetard fail.
All standards are optional. By your logic, there are no standards.
In this particular case of using a hash-bang with/bin/sh, I don't know of any actual written standard, but it's pretty well-known for the sake of portability (and POSIX defines the shell language for sh, not bash).
That address is a link-local address. The number following the percent sign is the zone index, which specifies which network interface the address is on. If it were not there, the address may be ambiguous with multiple interfaces (imagine if two hosts on two different network segments had the same IP address; neither host can talk to the other but the machine you're on can talk to both through separate interfaces).
I don't think IPv4 handles this case at all. Indeed, RFC 3927 discusses address ambiguity but provides no real solution for it. IPv6 provides a solution in the form of zone indices.
You telling your computer to fetch the data you have no license to and make a copy of it (in memory or on permanent storage) is a copyright violation.
Like it or not.
Wait, are you telling me that the way my DVD buffers in vram before being displayed is illegal? Because it's technically copied into vram before being displayed...
No, because the drive/software are licensed to do that.
Try harder!
No, because copyright law explicitly allows this type of copying!
Not necessarily a bug, it could be just a way the memory is used, with data and instructions not being properly separated, then maybe you could access instructions by overwriting memory, and normal buffer overflow, but it doesn't have to be a bug, just lack of security features.
In my day (and I'm not that old) we would call that a bug.
I'd consider those "ads" to be more accurately described as "credits". If an organization writes a driver (or pays someone else to do so), don't you think they are allowed to be credited?
Some courts have held that copying from a hard drive to RAM counts as a copy, for the purpose of copyright infringement. When you're already on the losing side for breach of contract, I wouldn't want to be on the side who may have to file potential appeals about copyright infringement.
Interesting, considering that copyright explicitly permits making copies of software as part of the installation/execution process. See USC chapter 1, section 117:
Limitations on exclusive rights: Computer programs (a) Making of Additional Copy or Adaptation by Owner of Copy.--Notwithstanding the provisions of section 106, it is not an infringement for the owner of a copy of a computer program to make or authorize the making of another copy or adaptation of that computer program provided: (1) that such a new copy or adaptation is created as an essential step in the utilization of the computer program in conjunction with a machine and that it is used in no other manner, or (2) that such new copy or adaptation is for archival purposes only and that all archival copies are destroyed in the event that continued possession of the computer program should cease to be rightful
However, you would be in breach of the software license, so you would have to delete the iBook software from your machine, or else you would be liable for copyright infringement of their software.
Why would you be liable for copyright infringement on their software? You're not redistributing it or anything else prohibited by copyright law. At the most you'd be liable for breaking a contract (the EULA), but in the absence of the contract you have full rights, as far as copyright law is concerned, to use the software (copyright law doesn't cover the use of software, hence the name copyright).
As I recall, the MySQL server install is only free for non-commercial use. Read the license agreement. Non-profit may not mean non-commercial so check with your lawyer. I also recommend using postgresql. The online documentation (http://www.postgresql.org/docs/9.1/interactive/index.html) is great so no need to pay for any training. I last used postgresql four years ago for a GIS application.
I think you recall incorrectly. MySQL is licensed under the GNU GPL, which means it can be used for any purpose (the GPL covers only the redistribution, not the use, of software). Since the OP intends to use MySQL in-house, its license is irrelevant.
That's a good, concise distinction between the two.
For a while now I've maintained that EULA's (but not free software licenses because, as you pointed out, are different from EULA's) are bunk anyway, in the vast majority of cases. Copyright law explicitly grants to end users the right to make copies of software as necessary to use the software, so what other rights or permissions does an EULA grant to the end user? If you (as an end user) don't agree to the EULA, then you can still legally use the software and are not bound by any of its terms and conditions*. Requiring the user to accept the terms before installing the software is merely a technical hurdle, not a legal one.
* Copying and distributing software is covered by copyright, so an EULA doesn't add any protection in that area that isn't already in law.
No EULA is required to use free software. DISTRIBUTING software is a different matter. It's an important difference.
Not entirely. The EULA (that is, the GPL) is why I can make copies of my Linux install CDs and give them to friends. It is legal and it is not piracy because of the "EULA". You don't have to be a developer for this to apply to you.
You're stating the exact same thing as the parent you replied to. What are you doing when you "make copies of my Linux install CDs and give them to friends"? You're DISTRIBUTING it. The GPL (which is not a EULA because it doesn't apply to the end-user but to anyone distributing it) gives permission to distribute the software with a few conditions on such distribution.
Whereas with the EULA that comes with Windows, no such right is granted and doing that would be illegal piracy and could land you in court.
Even in the absence of an EULA, it's still illegal. (Of course, an EULA almost invariably does not grant the user any additional rights (eg, to use the software) beyond what they already had in the absence of the EULA. But I'll save that discussion for another time.)
As a Linux outsider, it seems that the OSS community is hostile to people who want to make their living developing apps. It looks like support is an acceptable way to make a living, but being paid for the software you programmed is not.
Dick Stallman, better known as RMS, does not speak for all of us.
Even RMS is not opposed to people being paid for writing software. Employees at Redhat, Google, and many other companies are paid to write free software, and neither RMS nor the GNU GPL are opposed to that. Don't you think that the GPL would restrict selling software or being paid for writing software if RMS were opposed to it? It doesn't, and he is not.
Welcome to the year of the linux desktop, where stuff breaks if you don't keep everything local. If you remove structure it is really hard to get it back if not impossible. It isn't hard to maintain that structure, but apparently many many programmers don't even bother with the output from or input to autoconf/automake whatever. This isn't a problem with the filesystem hierarchie, but with programmers that don't even know how the tools of their choice works. The 'user' isn't even using $PATH anymore: Programs land in a database and/or menu and are launched by click.
Last time I checked, most of my shortcuts that are "launched by click" don't specify the full path to the executable. Take a shortcut to Firefox as an example. The command is just "firefox" (plus possibly some switches and options). When I click on the shortcut, the underlying system (Gnome or whatever) searches the PATH environment variable for that executable and runs the first instance that it finds, in the same way a shell would do (of course, Gnome technically is a shell too). This means if I install a different version of Firefox under/usr/local/bin, the system then runs that version instead, just as it should (because/usr/local/bin comes before/usr/bin in PATH).
I hope people will start to remember why such a structrure was introduced and keep the old functionality. My last personal oh crap moment came when debian changed their libc and people could no longer write to directories they only had group write rights to. How about regression tests?
How would a change in the libc affect whether users can write to directories? The C library doesn't determine file/directory access; if it did, it would be extremely easy for a program to get around file permissions by using a different C library, or by not using a C library at all. It sounds like either the permissions or groups changed (see/etc/groups), or SE Linux stuff (which I don't believe is necessary for most users) is getting in the way.
Compared to Lightroom. Like a tricycle compared to a reliable Ferrari. Give me a break.
It's more like comparing a family sedan to a Ferrari (which relatively few people can afford). They're reasonably priced (free!) and have all the basic features needed for PERSONAL photo management. Besides, what CRITICAL features are these photo managers, combined with other software like Rawstudio, missing that Lightroom has (for personal use, mind you)? It can't be noise reduction; Rawstudio has decent noise reduction. Lens correction? Rawstudio has that too. It can't be ease of use either; Rawstudio Shotwell, and F-Spot are all pretty easy to use.
There's no personal photo management and editing software for Linux? I guess I better tell the developers of F-Spot, Shotwell, and Darktable (and perhaps a few other projects too) that they don't exist. I personally use Shotwell; I used F-Spot for awhile, but older versions of F-Spot had show-stopping bugs for me. Shotwell has transparent RAW conversion and a few basic editing options. It's easy to open photos in a "real" editor (eg, Raw Studio or GIMP) for more extensive work, but for many photos it's sufficient.
Likewise with video editing software. Lately I haven't had much need to edit videos (other than transcoding or basic effects, which is easily done with ffmpeg or mencoder), but I know that video editing software does exist for Linux. Kdenlive is one that I've used most recently. It's not bad. Then there's Cinelerra, which is supposed to be the most advanced NL video editor available for Linux. I used it once in the past, but it was sluggish on my antiquated hardware at the time. I know there's a few other NL video editors out there for Linux, but I can't recall their names at the moment.
For vector graphics, there's Inkscape.
For that legacy in-house Windows-only software for which you lost the source (shame on you for losing it in the first place!), there's Wine. But frankly, if you lose internal source code that easily, good luck keeping track of all those software licenses!
At work, I use VS2010 Express for one of my projects, and if the full version is anything like it, I say "no thanks". It's buggy (especially the Intellisense, which is more like Nonsense sometimes), and the editor itself is nothing to write home about. I also use Netbeans for both Java (a fairly large Java project at that) and C++, and it's a far better IDE. But for this one project I have to use some Microsoft header files which don't work with GCC (some of their headers have syntax errors!), which is why I use VS2010 Express. Of course, I could probably use the VC dev tools in Netbeans, but that just seems wrong for some reason.
So really, it seems like you've been living under a rock (or under Microsoft's shadow, which is roughly equivalent) for several years when it comes to Linux. Either that, or you're a troll. Take your pick.
I think you missed the point of the analogy. The statement can be reworded as:
Calculator is to No RPN as Computer is to Only Runs Windows
In other words, No RPN (that is, only infix or algebraic notation) is like Windows, both of which can be seen as limitations of their respective devices.
The *size* of a photon in the visible region is much larger than an atom. Blue light is in the 400nm range while an atoms radius is in the 0.1nm range. So a photon intersects many atoms.. often all at once.
What you say about blue light (400nm) is its wavelength, not the size of the photon itself. Size and wavelength are separate properties. I could be wrong, of course (I am not particularly familiar with quantum mechanics and such).
If you do decide to download the full images, keep this in mind: Each tile image is between about 15KB and 50KB or so (let's say 30KB average), so the full detail image consists of roughly 9 gigabytes of JPEG images. Please, everyone, for the sake of their servers don't try to download it all at once! (I would personally try to trickle download it over the course of a week or so to be nice on their servers.)
The URL, again, is relative (to the XML file) and points to http://www.haltadefinizione.com/immagini/opere/10/imgfull/venere_krpano/l7_%250v_%250h.jpg, where %0v and %0h are the vertical and horizontal coordinates, respectively. Since this level is 181273 pixels wide and 113625 pixels (taken from the "level" tag), and tiles are 256x256 pixels (taken from the "image" tag), you can grab all images at this level with the fusker string http://www.haltadefinizione.com/immagini/opere/10/imgfull/venere_krpano/l7_[01-444]_[01-709].jpg. Be careful downloading the whole picture at this detail level (7). It's 314,796 tiles! If you just want a wallpaper-sized image for this image, try downloading detail level 1, which is 2833x1776 pixels (84 tiles) (fusker string: http://www.haltadefinizione.com/immagini/opere/10/imgfull/venere_krpano/l1_[01-07]_[01-12].jpg).
By the way, the watermarks are all embedded directly in the tile sets, unfortunately. They seem to be stamped on every tile whose coordinates modulo 4 are 0, meaning only 1/16 of the images are stamped.
2. Recursive strace: Currently it is not possible to run "strace" on a process which is already being straced. So for example: "strace -f strace -f ls" will not work (you'll get an "operation not permitted" inside the first strace. This makes it impossible for programs to use strace (or the related ptrace system call), since other programs which might also use strace, may depend on them.
Hi Alex, I think you meant strace'ing a process multiple times, rather than recursive strace'ing. You can certainly use ptrace on a process that is using ptrace on another process, but the issue is trying to ptrace a process that is already being ptrace'd. In other words:
x -> y -> z
(x, y, z are processes, -> means tracing) works, but
x -> z <- y
does not work because process "z" can be traced only once. I think the technical reason a process can be traced only once is because only one parent can receive the process's state via the wait() system call, much like only one process can receive its child's exit status via wait() in a non-ptrace situation. There may be other reasons for it as well, but I couldn't locate the POSIX standards (IEEE 1003.4 Realtime Extensions, I believe) detailing the ptrace() system call and its rationale.
If I misunderstood what you meant about recursive strace, then I do apologize.
Slashdot Mirror
SELinux is not needed for sudo to work (sudo was created about 18 years before SELinux). And "sudo -i" is preferable to "sudo su", by the way.
Can you tell a 15kHz sine wave from a 15kHz sawtooth wave? A CD can't, because there are only three samples per crest and almost every teenager can easily hear 15kHz.
Even a teenager cannot tell the difference between a 15kHz sine wave and a 15kHz sawtooth wave. The first harmonic of a 15kHz sawtooth wave above the fundamental frequency is at 30kHz. Please don't tell me that you believe that any human can hear frequencies that high.
Please make standard-compliant shell-scripts, use #!/bin/sh
Something in freetard-land is standard? Oh please, do tell. Which standard? Who has to follow the standard? If no one has to follow it, then it's not a standard. Freetard fail.
All standards are optional. By your logic, there are no standards.
In this particular case of using a hash-bang with /bin/sh, I don't know of any actual written standard, but it's pretty well-known for the sake of portability (and POSIX defines the shell language for sh, not bash).
That address is a link-local address. The number following the percent sign is the zone index, which specifies which network interface the address is on. If it were not there, the address may be ambiguous with multiple interfaces (imagine if two hosts on two different network segments had the same IP address; neither host can talk to the other but the machine you're on can talk to both through separate interfaces). I don't think IPv4 handles this case at all. Indeed, RFC 3927 discusses address ambiguity but provides no real solution for it. IPv6 provides a solution in the form of zone indices.
You telling your computer to fetch the data you have no license to and make a copy of it (in memory or on permanent storage) is a copyright violation. Like it or not.
Wait, are you telling me that the way my DVD buffers in vram before being displayed is illegal? Because it's technically copied into vram before being displayed ...
No, because the drive/software are licensed to do that. Try harder!
No, because copyright law explicitly allows this type of copying!
Not necessarily a bug, it could be just a way the memory is used, with data and instructions not being properly separated, then maybe you could access instructions by overwriting memory, and normal buffer overflow, but it doesn't have to be a bug, just lack of security features.
In my day (and I'm not that old) we would call that a bug.
I'd consider those "ads" to be more accurately described as "credits". If an organization writes a driver (or pays someone else to do so), don't you think they are allowed to be credited?
Some courts have held that copying from a hard drive to RAM counts as a copy, for the purpose of copyright infringement. When you're already on the losing side for breach of contract, I wouldn't want to be on the side who may have to file potential appeals about copyright infringement.
Interesting, considering that copyright explicitly permits making copies of software as part of the installation/execution process. See USC chapter 1, section 117:
Limitations on exclusive rights: Computer programs
(a) Making of Additional Copy or Adaptation by Owner of Copy.--Notwithstanding the provisions of section 106, it is not an infringement for the owner of a copy of a computer program to make or authorize the making of another copy or adaptation of that computer program provided:
(1) that such a new copy or adaptation is created as an essential step in the utilization of the computer program in conjunction with a machine and that it is used in no other manner, or
(2) that such new copy or adaptation is for archival purposes only and that all archival copies are destroyed in the event that continued possession of the computer program should cease to be rightful
However, you would be in breach of the software license, so you would have to delete the iBook software from your machine, or else you would be liable for copyright infringement of their software.
Why would you be liable for copyright infringement on their software? You're not redistributing it or anything else prohibited by copyright law. At the most you'd be liable for breaking a contract (the EULA), but in the absence of the contract you have full rights, as far as copyright law is concerned, to use the software (copyright law doesn't cover the use of software, hence the name copyright).
As I recall, the MySQL server install is only free for non-commercial use. Read the license agreement. Non-profit may not mean non-commercial so check with your lawyer. I also recommend using postgresql. The online documentation (http://www.postgresql.org/docs/9.1/interactive/index.html) is great so no need to pay for any training. I last used postgresql four years ago for a GIS application.
I think you recall incorrectly. MySQL is licensed under the GNU GPL, which means it can be used for any purpose (the GPL covers only the redistribution, not the use, of software). Since the OP intends to use MySQL in-house, its license is irrelevant.
That's a good, concise distinction between the two.
For a while now I've maintained that EULA's (but not free software licenses because, as you pointed out, are different from EULA's) are bunk anyway, in the vast majority of cases. Copyright law explicitly grants to end users the right to make copies of software as necessary to use the software, so what other rights or permissions does an EULA grant to the end user? If you (as an end user) don't agree to the EULA, then you can still legally use the software and are not bound by any of its terms and conditions*. Requiring the user to accept the terms before installing the software is merely a technical hurdle, not a legal one.
* Copying and distributing software is covered by copyright, so an EULA doesn't add any protection in that area that isn't already in law.
No EULA is required to use free software. DISTRIBUTING software is a different matter. It's an important difference.
Not entirely. The EULA (that is, the GPL) is why I can make copies of my Linux install CDs and give them to friends. It is legal and it is not piracy because of the "EULA". You don't have to be a developer for this to apply to you.
You're stating the exact same thing as the parent you replied to. What are you doing when you "make copies of my Linux install CDs and give them to friends"? You're DISTRIBUTING it. The GPL (which is not a EULA because it doesn't apply to the end-user but to anyone distributing it) gives permission to distribute the software with a few conditions on such distribution.
Whereas with the EULA that comes with Windows, no such right is granted and doing that would be illegal piracy and could land you in court.
Even in the absence of an EULA, it's still illegal. (Of course, an EULA almost invariably does not grant the user any additional rights (eg, to use the software) beyond what they already had in the absence of the EULA. But I'll save that discussion for another time.)
Dick Stallman, better known as RMS, does not speak for all of us.
Even RMS is not opposed to people being paid for writing software. Employees at Redhat, Google, and many other companies are paid to write free software, and neither RMS nor the GNU GPL are opposed to that. Don't you think that the GPL would restrict selling software or being paid for writing software if RMS were opposed to it? It doesn't, and he is not.
Welcome to the year of the linux desktop, where stuff breaks if you don't keep everything local. If you remove structure it is really hard to get it back if not impossible. It isn't hard to maintain that structure, but apparently many many programmers don't even bother with the output from or input to autoconf/automake whatever. This isn't a problem with the filesystem hierarchie, but with programmers that don't even know how the tools of their choice works. The 'user' isn't even using $PATH anymore: Programs land in a database and/or menu and are launched by click.
Last time I checked, most of my shortcuts that are "launched by click" don't specify the full path to the executable. Take a shortcut to Firefox as an example. The command is just "firefox" (plus possibly some switches and options). When I click on the shortcut, the underlying system (Gnome or whatever) searches the PATH environment variable for that executable and runs the first instance that it finds, in the same way a shell would do (of course, Gnome technically is a shell too). This means if I install a different version of Firefox under /usr/local/bin, the system then runs that version instead, just as it should (because /usr/local/bin comes before /usr/bin in PATH).
I hope people will start to remember why such a structrure was introduced and keep the old functionality. My last personal oh crap moment came when debian changed their libc and people could no longer write to directories they only had group write rights to. How about regression tests?
How would a change in the libc affect whether users can write to directories? The C library doesn't determine file/directory access; if it did, it would be extremely easy for a program to get around file permissions by using a different C library, or by not using a C library at all. It sounds like either the permissions or groups changed (see /etc/groups), or SE Linux stuff (which I don't believe is necessary for most users) is getting in the way.
F-Spot, Shotwell, and Darktable
Compared to Lightroom. Like a tricycle compared to a reliable Ferrari. Give me a break.
It's more like comparing a family sedan to a Ferrari (which relatively few people can afford). They're reasonably priced (free!) and have all the basic features needed for PERSONAL photo management. Besides, what CRITICAL features are these photo managers, combined with other software like Rawstudio, missing that Lightroom has (for personal use, mind you)? It can't be noise reduction; Rawstudio has decent noise reduction. Lens correction? Rawstudio has that too. It can't be ease of use either; Rawstudio Shotwell, and F-Spot are all pretty easy to use.
There's no personal photo management and editing software for Linux? I guess I better tell the developers of F-Spot, Shotwell, and Darktable (and perhaps a few other projects too) that they don't exist. I personally use Shotwell; I used F-Spot for awhile, but older versions of F-Spot had show-stopping bugs for me. Shotwell has transparent RAW conversion and a few basic editing options. It's easy to open photos in a "real" editor (eg, Raw Studio or GIMP) for more extensive work, but for many photos it's sufficient.
Likewise with video editing software. Lately I haven't had much need to edit videos (other than transcoding or basic effects, which is easily done with ffmpeg or mencoder), but I know that video editing software does exist for Linux. Kdenlive is one that I've used most recently. It's not bad. Then there's Cinelerra, which is supposed to be the most advanced NL video editor available for Linux. I used it once in the past, but it was sluggish on my antiquated hardware at the time. I know there's a few other NL video editors out there for Linux, but I can't recall their names at the moment.
For vector graphics, there's Inkscape.
For that legacy in-house Windows-only software for which you lost the source (shame on you for losing it in the first place!), there's Wine. But frankly, if you lose internal source code that easily, good luck keeping track of all those software licenses!
At work, I use VS2010 Express for one of my projects, and if the full version is anything like it, I say "no thanks". It's buggy (especially the Intellisense, which is more like Nonsense sometimes), and the editor itself is nothing to write home about. I also use Netbeans for both Java (a fairly large Java project at that) and C++, and it's a far better IDE. But for this one project I have to use some Microsoft header files which don't work with GCC (some of their headers have syntax errors!), which is why I use VS2010 Express. Of course, I could probably use the VC dev tools in Netbeans, but that just seems wrong for some reason.
So really, it seems like you've been living under a rock (or under Microsoft's shadow, which is roughly equivalent) for several years when it comes to Linux. Either that, or you're a troll. Take your pick.
Yes, clearly everyone here is an idiot (except you, of course). Did you sign up on /. just to point out all the idiots?
You still missed the point of the analogy, by the way.
I think you missed the point of the analogy. The statement can be reworded as:
In other words, No RPN (that is, only infix or algebraic notation) is like Windows, both of which can be seen as limitations of their respective devices.
tl;dr version: Whooooosh!
The *size* of a photon in the visible region is much larger than an atom. Blue light is in the 400nm range while an atoms radius is in the 0.1nm range. So a photon intersects many atoms.. often all at once.
What you say about blue light (400nm) is its wavelength, not the size of the photon itself. Size and wavelength are separate properties. I could be wrong, of course (I am not particularly familiar with quantum mechanics and such).
If you do decide to download the full images, keep this in mind: Each tile image is between about 15KB and 50KB or so (let's say 30KB average), so the full detail image consists of roughly 9 gigabytes of JPEG images. Please, everyone, for the sake of their servers don't try to download it all at once! (I would personally try to trickle download it over the course of a week or so to be nice on their servers.)
Look at the source code of (for example) http://www.haltadefinizione.com/magnifier.jsp?idopera=10. In there you'll find this code:
swf.addVariable("xml","/immagini/opere/10/imgfull/properties_krpano.xml");
That's a relative address—the full URL is http://www.haltadefinizione.com/immagini/opere/10/imgfull/properties_krpano.xml. That file contains stuff like this:
The URL, again, is relative (to the XML file) and points to http://www.haltadefinizione.com/immagini/opere/10/imgfull/venere_krpano/l7_%250v_%250h.jpg, where %0v and %0h are the vertical and horizontal coordinates, respectively. Since this level is 181273 pixels wide and 113625 pixels (taken from the "level" tag), and tiles are 256x256 pixels (taken from the "image" tag), you can grab all images at this level with the fusker string http://www.haltadefinizione.com/immagini/opere/10/imgfull/venere_krpano/l7_[01-444]_[01-709].jpg. Be careful downloading the whole picture at this detail level (7). It's 314,796 tiles! If you just want a wallpaper-sized image for this image, try downloading detail level 1, which is 2833x1776 pixels (84 tiles) (fusker string: http://www.haltadefinizione.com/immagini/opere/10/imgfull/venere_krpano/l1_[01-07]_[01-12].jpg).
By the way, the watermarks are all embedded directly in the tile sets, unfortunately. They seem to be stamped on every tile whose coordinates modulo 4 are 0, meaning only 1/16 of the images are stamped.
Happy downloading!
That's easy to win. Just start the program like this:
GOTO 20
"Honestly honey, I wasn't looking at porn, I was applying for work at Research In Motion. Seriously, I'd love to get a RIM job..."
Then you'll be happy to know that this site exists...
(Yes, it is Safe For Work!)
2. Recursive strace: Currently it is not possible to run "strace" on a process which is already being straced. So for example: "strace -f strace -f ls" will not work (you'll get an "operation not permitted" inside the first strace. This makes it impossible for programs to use strace (or the related ptrace system call), since other programs which might also use strace, may depend on them.
Hi Alex, I think you meant strace'ing a process multiple times, rather than recursive strace'ing. You can certainly use ptrace on a process that is using ptrace on another process, but the issue is trying to ptrace a process that is already being ptrace'd. In other words:
x -> y -> z
(x, y, z are processes, -> means tracing) works, but
x -> z <- y
does not work because process "z" can be traced only once. I think the technical reason a process can be traced only once is because only one parent can receive the process's state via the wait() system call, much like only one process can receive its child's exit status via wait() in a non-ptrace situation. There may be other reasons for it as well, but I couldn't locate the POSIX standards (IEEE 1003.4 Realtime Extensions, I believe) detailing the ptrace() system call and its rationale.
If I misunderstood what you meant about recursive strace, then I do apologize.
Last time I checked, insects were in the animal kingdom, so PETA should still have "jurisdiction" over them.