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@ -60,7 +60,7 @@ these issues have been solved using block allocaiton instead of continuous alloc
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## system calls for file systems
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## system calls for file systems
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- open close, read, write, ioctl, etc
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- open close, read, write, ioctl, etc
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`ssize_t write(int fd, const, void *buf, size_t count)`
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`ssize_t write(int fd, const void *buf, size_t count)`
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- fd - file descriptor
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- fd - file descriptor
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- write up to count butes from the buffer pointed buf to the file referred to by the file descriptor
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- write up to count butes from the buffer pointed buf to the file referred to by the file descriptor
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- returns -1 if error. and errno is set
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- returns -1 if error. and errno is set
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@ -82,7 +82,6 @@ these issues have been solved using block allocaiton instead of continuous alloc
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you can give *advice* to the OS about how to read the file by specifying sequential or direct
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you can give *advice* to the OS about how to read the file by specifying sequential or direct
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# directory structure
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# directory structure
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tree structured
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tree structured
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9
content/notes/204-questions.md
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9
content/notes/204-questions.md
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@ -0,0 +1,9 @@
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---
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title: "204-questions"
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aliases:
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tags:
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---
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1. in read and write system calls why is the buffer const in write and not in read
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2.
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@ -7,6 +7,20 @@ tags:
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A file is a collection of related data. They can be thought of as artifacts of the dialogue between the user and the OS
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A file is a collection of related data. They can be thought of as artifacts of the dialogue between the user and the OS
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# Attributes
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The attributes of a file are stored in an index node (inode) which held in a directory. These attributes include: name, owner, type, location, size, permissions, more.
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The attributes of a file are stored in an index node (inode) which held in a directory. These attributes include: name, owner, type, location, size, permissions, more.
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There are two main systems calls for file interaction: write and read
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# System Calls
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There are two main systems calls for file interaction: write and read.
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# File Access patterns
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There are two main types of access: **Sequential** and **Direct** access.
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In sequential access, a file pointer specifies a record within the file. The pointer can then be moved forward (read or write) or backwards (rewind).
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In direct access, a file is viewed as a numbered sequence of records. Operations can be done on any record in any order.
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# Directory structure
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# Disk allocation methods
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