Verzeichnis umbenennen
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Kann man dann davon ausgehen, dass im Prinzip ein (gemountetes) Laufwerk auch mit einem Filedeskriptor angesprochen werden kann?
Wobei sich mir dann gleich die Frage aufdrängt, wie man ein Laufwerk mittels Code(C/C++) mountet. Aber da findet man vielleicht auch was mit dr Suche oder FAQ.
Danke jedenfalls für die Info.
Tschau arni
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arni schrieb:
Kann man dann davon ausgehen, dass im Prinzip ein (gemountetes) Laufwerk auch mit einem Filedeskriptor angesprochen werden kann?
Ein Laufwerk selbst ist auch nur eine spezielle Art von Datei unterhalb von /dev. Zum Beispiel eine zweite Festplatte, die als /dev/hdb1 (erste primäre Partition auf dem Master des zweiten IDE Kanal) angesprochen werden kann und die du auf einen normalen Filedescriptor (= Mountpoint) z.B. nach /mnt/data mountest.
arni schrieb:
Wobei sich mir dann gleich die Frage aufdrängt, wie man ein Laufwerk mittels Code(C/C++) mountet.
siehe Manpages mount(2) und umount(2)
MOUNT(2) Linux Programmer's Manual MOUNT(2) NAME mount, umount - mount and unmount filesystems. SYNOPSIS #include <sys/mount.h> int mount(const char *specialfile, const char * dir , const char * filesystemtype, unsigned long mountflags , const void * data); int umount(const char *dir); DESCRIPTION mount attaches the filesystem specified by specialfile (which is often a device name) to the directory specified by dir. umount removes the attachment of the (topmost) filesystem mounted on dir. Only the super-user may mount and unmount filesystems. The filesystemtype argument may take one of the values listed in /proc/filesystems (like "minix", "ext2", "msdos", "proc", "nfs", "iso9660" etc.). The mountflags argument may have the magic number 0xC0ED in the top 16 bits, and various mount flags (as defined in <linux/fs.h> for libc4 and libc5 and in <sys/mount.h> for glibc2) in the low order 16 bits: #define MS_RDONLY 1 /* mount read-only */ #define MS_NOSUID 2 /* ignore suid and sgid bits */ #define MS_NODEV 4 /* no access to device special files */ #define MS_NOEXEC 8 /* no program execution */ #define MS_SYNCHRONOUS 16 /* writes are synced at once */ #define MS_REMOUNT 32 /* alter flags of a mounted fs */ #define MS_MANDLOCK 64 /* allow mandatory locks */ #define MS_NOATIME 1024 /* do not update access times */ #define MS_NODIRATIME 2048 /* do not update dir access times */ #define MS_BIND 4096 /* bind subtree elsewhere */ The data argument is interpreted by the different file systems. RETURN VALUE On success, zero is returned. On error, -1 is returned, and errno is set appropriately. ERRORS The error values given below result from filesystem type independent errors. Each filesystem type may have its own special errors and its own special behavior. See the kernel source code for details. EPERM The user is not the super-user. ENODEV Filesystemtype not configured in the kernel. ENOTBLK Specialfile is not a block device (if a device was required). EBUSY Specialfile is already mounted. Or, it cannot be remounted read- only, because it still holds files open for writing. Or, it cannot be mounted on dir because dir is still busy (it is the working directory of some task, the mount point of another device, has open files, etc.). EINVAL Specialfile had an invalid superblock. Or, a remount was attempted, while specialfile was not already mounted on dir. Or, an umount was attempted, while dir was not a mount point. EFAULT One of the pointer arguments points outside the user address space. ENOMEM The kernel could not allocate a free page to copy filenames or data into. ENAMETOOLONG A pathname was longer than MAXPATHLEN. ENOENT A pathname was empty or had a nonexistent component. ENOTDIR The second argument, or a prefix of the first argument, is not a directory. EACCES A component of a path was not searchable. Or, mounting a read-only filesystem was attempted without giving the MS_RDONLY flag. Or, the block device Specialfile is located on a filesystem mounted with the MS_NODEV option. ENXIO The major number of the block device specialfile is out of range. EMFILE (In case no block device is required:) Table of dummy devices is full. CONFORMING TO These functions are Linux-specific and should not be used in programs intended to be portable. HISTORY The original umount function was called as umount(device) and would return ENOTBLK when called with something other than a block device. In Linux 0.98p4 a call umount(dir) was added, in order to support anonymous devices. In Linux 2.3.99-pre7 the call umount(device) was removed, leaving only umount(dir) (since now devices can be mounted in more than one place, so specifying the device does not suffice). The original MS_SYNC flag was renamed MS_SYNCHRONOUS in 1.1.69 when a different MS_SYNC was added to <mman.h>. SEE ALSO mount(8), umount(8)Als Ergänzung noch die gleiche Manpage aus BSD:
MOUNT(2) FreeBSD System Calls Manual MOUNT(2) NAME mount, unmount - mount or dismount a file system LIBRARY Standard C Library (libc, -lc) SYNOPSIS #include <sys/param.h> #include <sys/mount.h> int mount(const char *type, const char *dir, int flags, void *data); int unmount(const char *dir, int flags); DESCRIPTION The mount() function grafts a file system object onto the system file tree at the point dir. The argument data describes the file system object to be mounted. The argument type tells the kernel how to inter- pret data (See type below). The contents of the file system become available through the new mount point dir. Any files in dir at the time of a successful mount are swept under the carpet so to speak, and are unavailable until the file system is unmounted. The following flags may be specified to suppress default semantics which affect file system access. MNT_RDONLY The file system should be treated as read-only; Even the super-user may not write on it. MNT_NOEXEC Do not allow files to be executed from the file system. MNT_NOSUID Do not honor setuid or setgid bits on files when execut- ing them. MNT_NODEV Do not interpret special files on the file system. MNT_UNION Union with underlying filesystem instead of obscuring it. MNT_SYNCHRONOUS All I/O to the file system should be done synchronously. MNT_ASYNC All I/O to the file system should be done asyn- chronously. MNT_NOCOREDUMP Do not allow programs to dump core files on the file system. MNT_NOATIME Never update access time in the file system. MNT_SYMPERM Recognize the permission of symbolic link when reading or traversing. MNT_NODEVMTIME Never update modification time of device files. MNT_SOFTDEP Use soft dependencies. The flag MNT_UPDATE indicates that the mount command is being applied to an already mounted file system. This allows the mount flags to be changed without requiring that the file system be unmounted and remounted. Some file systems may not allow all flags to be changed. For example, most file systems will not allow a change from read-write to read-only. The type argument defines the type of the file system. The types of file systems known to the system are defined in <sys/mount.h>. data is a pointer to a structure that contains the type specific arguments to mount. The currently supported types of file systems and their type spe- cific data are: MOUNT_FFS struct ufs_args { char *fspec; /* block special file to mount */ struct export_args export; /* network export information */ }; MOUNT_NFS struct nfs_args { int version; /* args structure version */ struct sockaddr *addr; /* file server address */ int addrlen; /* length of address */ int sotype; /* Socket type */ int proto; /* and Protocol */ u_char *fh; /* File handle to be mounted */ int fhsize; /* Size, in bytes, of fh */ int flags; /* flags */ int wsize; /* write size in bytes */ int rsize; /* read size in bytes */ int readdirsize; /* readdir size in bytes */ int timeo; /* initial timeout in .1 secs */ int retrans; /* times to retry send */ int maxgrouplist; /* Max. size of group list */ int readahead; /* # of blocks to readahead */ int leaseterm; /* Term (sec) of lease */ int deadthresh; /* Retrans threshold */ char *hostname; /* server's name */ }; MOUNT_MFS struct mfs_args { char *fspec; /* name to export for statfs */ struct export_args export; /* if we can export an MFS */ caddr_t base; /* base of file system in mem */ u_long size; /* size of file system */ }; The unmount() function call disassociates the file system from the speci- fied mount point dir. The flags argument may specify MNT_FORCE to specify that the file system should be forcibly unmounted even if files are still active. Active spe- cial devices continue to work, but any further accesses to any other active files result in errors even if the file system is later remounted. RETURN VALUES mount() returns the value 0 if the mount was successful, otherwise -1 is returned and the variable errno is set to indicate the error. unmount() returns the value 0 if the unmount succeeded; otherwise -1 is returned and the variable errno is set to indicate the error. ERRORS mount() will fail when one of the following occurs: [EPERM] The caller is not the super-user. [ENAMETOOLONG] A component of a pathname exceeded {NAME_MAX} charac- ters, or an entire path name exceeded {PATH_MAX} char- acters. [ELOOP] Too many symbolic links were encountered in translat- ing a pathname. [ENOENT] A component of dir does not exist. [ENOTDIR] A component of name is not a directory, or a path pre- fix of special is not a directory. [EBUSY] Another process currently holds a reference to dir. [EFAULT] dir points outside the process's allocated address space. The following errors can occur for a ufs file system mount: [ENODEV] A component of ufs_args fspec does not exist. [ENOTBLK] Fspec is not a block device. [ENXIO] The major device number of fspec is out of range (this indicates no device driver exists for the associated hardware). [EBUSY] Fspec is already mounted. [EMFILE] No space remains in the mount table. [EINVAL] The super block for the file system had a bad magic number or an out of range block size. [ENOMEM] Not enough memory was available to read the cylinder group information for the file system. [EIO] An I/O error occurred while reading the super block or cylinder group information. [EFAULT] Fspec points outside the process's allocated address space. The following errors can occur for a nfs file system mount: [ETIMEDOUT] Nfs timed out trying to contact the server. [EFAULT] Some part of the information described by nfs_args points outside the process's allocated address space. The following errors can occur for a mfs file system mount: [EMFILE] No space remains in the mount table. [EINVAL] The super block for the file system had a bad magic number or an out of range block size. [ENOMEM] Not enough memory was available to read the cylinder group information for the file system. [EIO] A paging error occurred while reading the super block or cylinder group information. [EFAULT] Name points outside the process's allocated address space. unmount() may fail with one of the following errors: [EPERM] The caller is not the super-user. [ENOTDIR] A component of the path is not a directory. [ENAMETOOLONG] A component of a pathname exceeded {NAME_MAX} charac- ters, or an entire path name exceeded {PATH_MAX} char- acters. [ELOOP] Too many symbolic links were encountered in translat- ing the pathname. [EINVAL] The requested directory is not in the mount table. [EBUSY] A process is holding a reference to a file located on the file system. [EIO] An I/O error occurred while writing cached file system information. [EFAULT] dir points outside the process's allocated address space. A ufs or mfs mount can also fail if the maximum number of file systems are currently mounted. SEE ALSO getfsstat(2), getmntinfo(3), symlink(7), mount(8), sysctl(8), umount(8) HISTORY The mount() and umount() (now unmount()) function calls appeared in Version 6 AT&T UNIX. BUGS Some of the error codes need translation to more obvious messages. FreeBSD 4.7 November 7, 1999 FreeBSD 4.7
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Um Verzeichnisse umzubenennen kann man auch einen Trick verwenden mit dem Befehl "move":
z.B.:
Verzeichnis heisst /home/test
test soll umbenannt werden in "nameneu"wechseln in das Verzeichnis /home dann:
Befehl: mv test nameneulg
theVOICE
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theVOICE schrieb:
Um Verzeichnisse umzubenennen kann man auch einen Trick verwenden mit dem Befehl "move":
Befehl: mv test nameneu
Es ging hier eigentlich um C-Programmierung.
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naja gut du hättest ja auch in deinem c-programm mv verwenden können oder nicht?
MFG eiskalt
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Wozu wenn das ganze auch portabel per (std::)rename geht?
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nman schrieb:
Wozu wenn das ganze auch portabel per (std::)rename geht?
...wobei zu beachten ist, dass ein rename() über Mountgrenzen (z.B. rename("/u01/oracle/tbs_system1.ora", "/u02/oracle/tbs_system2.ora") ) hinweg nicht funktioniert -- ein Aufruf von system() und "mv" hingegen schon.
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Descartes schrieb:
...wobei zu beachten ist, dass ein rename() über Mountgrenzen (z.B. rename("/u01/oracle/tbs_system1.ora", "/u02/oracle/tbs_system2.ora") ) hinweg nicht funktioniert -- ein Aufruf von system() und "mv" hingegen schon.
Also system() würde ich dafür auf keinen Fall verwenden da der Umweg über die Shell hierbei keinerlei Vorteile haben dürfte und ein exec und mv auch nur dann wenn feststeht dass eine Datei zwischen 2 verschiedenen Dateisystemen verschoben werden muss.
(Und dass rename sich so verhält kann man sich auch denken, schließlich operiert es (zumindest unter GNU/ Linux) normalerweise im Grunde nur auf Hardlinks, oder?)
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ist ja wirklich interessant, was man hier so alles lernen kann. Auch weil Vor- und Nachteile der verschiedenen Zugriffe mit angesprochen werden. Hätte noch zwei Fragen zu dem Thread:
Was sind Mountgrenzen? Ist damit der Zugriff auf verschiedene Hardware gemeint? also auf zwei verschiedene Festplatten zum Beispiel?
Und:
Der Zugang zu den Manpages ist mir ja klar, aber wie komme ich an das BSD-Manual heran? Die Quelle habe ich jetzt zum ersten Mal gesehen.
Danke arni
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da findest du alle möglichen Manpages