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Umask
In computing, umask is a command (computing), command that determines the settings of a Mask (computing), mask that controls how file permissions are set for newly created files. It may also affect how the file permissions are changed explicitly. is also a Function (computing), function that sets the mask, or it may refer to the mask itself, which is formally known as the ''file mode creation mask''. The mask is a grouping of bits, each of which restricts how its corresponding permission is set for newly created files. The bits in the mask may be changed by invoking the command. Overview In Unix-like systems, each file has a set of attributes that control who can read, write or execute it. When a program creates a file, the file permissions are restricted by the mask. If the mask has a bit set to "1", then the corresponding initial file permission will be ''disabled''. A bit set to "0" in the mask means that the corresponding permission will be ''determined by the program'' and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chmod
In Unix and Unix-like operating systems, is the command (computing), command and system call used to change the File-system permissions, access permissions and the #Special modes, special mode flags (the setuid, ''setuid'', ''setgid'', and sticky bit, ''sticky'' flags) of file system objects (Computer file, files and Directory (computing), directories). Collectively these were originally called its modes, and the name was chosen as an abbreviation of ''change mode''. History A command first appeared in AT&T Corporation, AT&T Unix, UNIX version 1, along with the system call. As systems grew in number and types of users, access-control lists were added to many file systems in addition to these most basic modes to increase flexibility. The version of bundled in GNU coreutils was written by David MacKenzie and Jim Meyering. The command is available as a separate package for Microsoft Windows as part of the UnxUtils collection of Native (computing), native Windows API, Win32 por ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chmod
In Unix and Unix-like operating systems, is the command (computing), command and system call used to change the File-system permissions, access permissions and the #Special modes, special mode flags (the setuid, ''setuid'', ''setgid'', and sticky bit, ''sticky'' flags) of file system objects (Computer file, files and Directory (computing), directories). Collectively these were originally called its modes, and the name was chosen as an abbreviation of ''change mode''. History A command first appeared in AT&T Corporation, AT&T Unix, UNIX version 1, along with the system call. As systems grew in number and types of users, access-control lists were added to many file systems in addition to these most basic modes to increase flexibility. The version of bundled in GNU coreutils was written by David MacKenzie and Jim Meyering. The command is available as a separate package for Microsoft Windows as part of the UnxUtils collection of Native (computing), native Windows API, Win32 por ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
File Permissions
Most file systems include attributes of files and directories that control the ability of users to read, change, navigate, and Execution (computing), execute the contents of the file system. In some cases, menu options or functions may be made visible or hidden depending on a user's permission level; this kind of user interface is referred to as permission-driven user interface, permission-driven. Two types of permissions are widely available: traditional Unix file system permissions and access-control lists (ACLs) which are capable of more specific control. File system variations The original File Allocation Table file system has a per-file all-user read-only attribute. NTFS implemented in Windows NT, Microsoft Windows NT and its derivatives, use ACLs to provide a complex set of permissions. OpenVMS uses a permission scheme similar to that of Unix. There are four categories (system, owner, group, and world) and four types of access permissions (Read, Write, Execute and Delete ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
File Permissions
Most file systems include attributes of files and directories that control the ability of users to read, change, navigate, and Execution (computing), execute the contents of the file system. In some cases, menu options or functions may be made visible or hidden depending on a user's permission level; this kind of user interface is referred to as permission-driven user interface, permission-driven. Two types of permissions are widely available: traditional Unix file system permissions and access-control lists (ACLs) which are capable of more specific control. File system variations The original File Allocation Table file system has a per-file all-user read-only attribute. NTFS implemented in Windows NT, Microsoft Windows NT and its derivatives, use ACLs to provide a complex set of permissions. OpenVMS uses a permission scheme similar to that of Unix. There are four categories (system, owner, group, and world) and four types of access permissions (Read, Write, Execute and Delete ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
File System Permissions
Most file systems include attributes of files and directories that control the ability of users to read, change, navigate, and execute the contents of the file system. In some cases, menu options or functions may be made visible or hidden depending on a user's permission level; this kind of user interface is referred to as permission-driven. Two types of permissions are widely available: traditional Unix file system permissions and access-control lists (ACLs) which are capable of more specific control. File system variations The original File Allocation Table file system has a per-file all-user read-only attribute. NTFS implemented in Microsoft Windows NT and its derivatives, use ACLs to provide a complex set of permissions. OpenVMS uses a permission scheme similar to that of Unix. There are four categories (system, owner, group, and world) and four types of access permissions (Read, Write, Execute and Delete). The categories are not mutually disjoint: World includes Group, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fmask
fstab (after ''file systems table'') is a system file commonly found in the directory /etc on Unix and Unix-like computer systems. In Linux, it is part of the util-linux package. The fstab file typically lists all available disk partitions and other types of file systems and data sources that may not necessarily be disk-based, and indicates how they are to be initialized or otherwise integrated into the larger file system structure. The fstab file is read by the mount command, which happens automatically at boot time to determine the overall file system structure, and thereafter when a user executes the mount command to modify that structure. It is the duty of the system administrator to properly create and maintain the fstab file. While fstab is used for basic system configuration, for other uses, it has been superseded by automatic mounting mechanisms. The file has other names on some versions of Unix; for example, it is found at /etc/vfstab on Solaris systems. Modern use Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fstab
fstab (after ''file systems table'') is a system file commonly found in the directory /etc on Unix and Unix-like computer systems. In Linux, it is part of the util-linux package. The fstab file typically lists all available disk partitions and other types of file systems and data sources that may not necessarily be disk-based, and indicates how they are to be initialized or otherwise integrated into the larger file system structure. The fstab file is read by the mount command, which happens automatically at boot time to determine the overall file system structure, and thereafter when a user executes the mount command to modify that structure. It is the duty of the system administrator to properly create and maintain the fstab file. While fstab is used for basic system configuration, for other uses, it has been superseded by automatic mounting mechanisms. The file has other names on some versions of Unix; for example, it is found at /etc/vfstab on Solaris systems. Modern use Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Setuid
The Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and ot ... access rights flags setuid and setgid (short for ''set user identity'' and ''set group identity'') allow users to run an executable with the file system permissions of the executable's owner or group respectively and to change behaviour in directories. They are often used to allow users on a computer system to run programs with temporarily elevated privileges in order to perform a specific task. While the assumed user id or group id privileges provided are not always elevated, at a minimum they are specific. The flags setuid and setgid are needed for tasks that require different privileges than what the user is normally granted, such as the ability to alter system files or databases to change their login password. Some of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Setgid
The Unix access rights flags setuid and setgid (short for ''set user identity'' and ''set group identity'') allow users to run an executable with the file system permissions of the executable's owner or group respectively and to change behaviour in directories. They are often used to allow users on a computer system to run programs with temporarily elevated privileges in order to perform a specific task. While the assumed user id or group id privileges provided are not always elevated, at a minimum they are specific. The flags setuid and setgid are needed for tasks that require different privileges than what the user is normally granted, such as the ability to alter system files or databases to change their login password. Some of the tasks that require additional privileges may not immediately be obvious, though, such as the ping command, which must send and listen for control packets on a network interface. File modes The setuid and setgid bits are normally represented as th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mask (computing)
In computer science, a mask or bitmask is data that is used for bitwise operations, particularly in a bit field. Using a mask, multiple bits in a byte, nibble, word, etc. can be set either on or off, or inverted from on to off (or vice versa) in a single bitwise operation. An additional use of masking involves predication in vector processing, where the bitmask is used to select which element operations in the vector are to be executed (mask bit is enabled) and which are not (mask bit is clear). Common bitmask functions Masking bits to 1 To turn certain bits on, the bitwise OR operation can be used, following the principle that Y OR 1 = 1 and Y OR 0 = Y. Therefore, to make sure a bit is on, OR can be used with a 1. To leave a bit unchanged, OR is used with a 0. Example: Masking ''on'' the higher nibble (bits 4, 5, 6, 7) while leaving the lower nibble (bits 0, 1, 2, 3) unchanged. 10010101 10100101 OR 11110000 11110000 = 11110101 11110101 Masking bits to 0 Mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UNIX
Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and others. Initially intended for use inside the Bell System, AT&T licensed Unix to outside parties in the late 1970s, leading to a variety of both academic and commercial Unix variants from vendors including University of California, Berkeley (Berkeley Software Distribution, BSD), Microsoft (Xenix), Sun Microsystems (SunOS/Solaris (operating system), Solaris), Hewlett-Packard, HP/Hewlett Packard Enterprise, HPE (HP-UX), and IBM (IBM AIX, AIX). In the early 1990s, AT&T sold its rights in Unix to Novell, which then sold the UNIX trademark to The Open Group, an industry consortium founded in 1996. The Open Group allows the use of the mark for certified operating systems that comply with the Single UNIX Specification (SUS). Unix systems are chara ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sticky Bit
In computing, the sticky bit is a user ownership File system permissions, access right Flag (computing), flag that can be assigned to Computer file, files and Directory (computing), directories on Unix-like systems. There are two definitions: one for files, one for directories. For files, particularly executables, superuser could tag these as to be retained in main memory, even when their need ends, to minimize swapping that would occur when another need arises, and the file now has to be reloaded from relatively slow secondary memory. This function has become obsolete due to swapping optimization. For directories, when a directory's sticky bit is set, the filesystem treats the files in such directories in a special way so only the file's owner, the directory's owner, or root user can rename or delete the file. Without the sticky bit set, any user with write and execute permissions for the directory can rename or delete contained files, regardless of the file's owner. Typically th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
