Some special files in Unix
Background
There are lots types of special files in Unix, for example symlinks, device files and proc files (under /proc). for proc files it is just a normal files or even text files. But for the rest, I only know how to use them, but I don't know their internal structure and what they are (in depth). And unfortunately, all the way to access file can only get the object which they are escaped for. In other words there is no way to get the content inside them.
Questions
For symlinks, there is no doubt that there is a string which store the paths of their targets. However, if there is only a string, how can they be distinguished from plaintext files? If there is special headers which are specified by filesystem drivers. What are them? Is there any convention about them? Can anyone tell me what is binary representation is about a symlink point at /usr/bin/bash?
For Device files (nod), What are their binary structure and representation? According their behaviors, they mush include the information about relevant interface number and drivers. But it will make their size greatly different. Can anyone explain it in binary level?
For compatibility of symlinks and device file (I know it is impossible for a same device file works in two different environment, but we can use our imagination to make an experiment) is the binary content of these files strongly depend on file system type and the kernel of operating system? For example is I copy (not via cp command), just write identical binary content ) to a different file system (like from ext4 to xfs), is this file (symlinks or device file) still valid and functional? How will it going when copy it from Linux machine to BSD machine?
Or they are not files, they are just special records in file system header part. What it actually is?
files filesystems symlink
asked 8 mins ago
davmosdavmos
7317
add a comment |
Background
There are lots types of special files in Unix, for example symlinks, device files and proc files (under /proc). for proc files it is just a normal files or even text files. But for the rest, I only know how to use them, but I don't know their internal structure and what they are (in depth). And unfortunately, all the way to access file can only get the object which they are escaped for. In other words there is no way to get the content inside them.
Questions
For symlinks, there is no doubt that there is a string which store the paths of their targets. However, if there is only a string, how can they be distinguished from plaintext files? If there is special headers which are specified by filesystem drivers. What are them? Is there any convention about them? Can anyone tell me what is binary representation is about a symlink point at /usr/bin/bash?
For Device files (nod), What are their binary structure and representation? According their behaviors, they mush include the information about relevant interface number and drivers. But it will make their size greatly different. Can anyone explain it in binary level?
For compatibility of symlinks and device file (I know it is impossible for a same device file works in two different environment, but we can use our imagination to make an experiment) is the binary content of these files strongly depend on file system type and the kernel of operating system? For example is I copy (not via cp command), just write identical binary content ) to a different file system (like from ext4 to xfs), is this file (symlinks or device file) still valid and functional? How will it going when copy it from Linux machine to BSD machine?
Or they are not files, they are just special records in file system header part. What it actually is?
files filesystems symlink
asked 8 mins ago
davmosdavmos
7317
add a comment |
Background
There are lots types of special files in Unix, for example symlinks, device files and proc files (under /proc). for proc files it is just a normal files or even text files. But for the rest, I only know how to use them, but I don't know their internal structure and what they are (in depth). And unfortunately, all the way to access file can only get the object which they are escaped for. In other words there is no way to get the content inside them.
Questions
For symlinks, there is no doubt that there is a string which store the paths of their targets. However, if there is only a string, how can they be distinguished from plaintext files? If there is special headers which are specified by filesystem drivers. What are them? Is there any convention about them? Can anyone tell me what is binary representation is about a symlink point at /usr/bin/bash?
For Device files (nod), What are their binary structure and representation? According their behaviors, they mush include the information about relevant interface number and drivers. But it will make their size greatly different. Can anyone explain it in binary level?
For compatibility of symlinks and device file (I know it is impossible for a same device file works in two different environment, but we can use our imagination to make an experiment) is the binary content of these files strongly depend on file system type and the kernel of operating system? For example is I copy (not via cp command), just write identical binary content ) to a different file system (like from ext4 to xfs), is this file (symlinks or device file) still valid and functional? How will it going when copy it from Linux machine to BSD machine?
Or they are not files, they are just special records in file system header part. What it actually is?
files filesystems symlink
asked 8 mins ago
davmosdavmos
7317
Background
There are lots types of special files in Unix, for example symlinks, device files and proc files (under /proc). for proc files it is just a normal files or even text files. But for the rest, I only know how to use them, but I don't know their internal structure and what they are (in depth). And unfortunately, all the way to access file can only get the object which they are escaped for. In other words there is no way to get the content inside them.
Questions
For symlinks, there is no doubt that there is a string which store the paths of their targets. However, if there is only a string, how can they be distinguished from plaintext files? If there is special headers which are specified by filesystem drivers. What are them? Is there any convention about them? Can anyone tell me what is binary representation is about a symlink point at /usr/bin/bash?
For Device files (nod), What are their binary structure and representation? According their behaviors, they mush include the information about relevant interface number and drivers. But it will make their size greatly different. Can anyone explain it in binary level?
For compatibility of symlinks and device file (I know it is impossible for a same device file works in two different environment, but we can use our imagination to make an experiment) is the binary content of these files strongly depend on file system type and the kernel of operating system? For example is I copy (not via cp command), just write identical binary content ) to a different file system (like from ext4 to xfs), is this file (symlinks or device file) still valid and functional? How will it going when copy it from Linux machine to BSD machine?
Or they are not files, they are just special records in file system header part. What it actually is?
files filesystems symlink
files filesystems symlink
asked 8 mins ago
davmosdavmos
7317
asked 8 mins ago
davmosdavmos
7317
asked 8 mins ago
davmosdavmos
7317
asked 8 mins ago
davmosdavmos
7317
asked 8 mins ago
davmosdavmos
7317
7317
add a comment |
add a comment |
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