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Minimum Values for File System Limits

Here are the names for the POSIX minimum upper bounds for some of the above parameters. The significance of these values is that you can safely push to these limits without checking whether the particular system you are using can go that far.

_POSIX_LINK_MAX
The most restrictive limit permitted by POSIX for the maximum value of a file's link count. The value of this constant is 8; thus, you can always make up to eight names for a file without running into a system limit.

_POSIX_MAX_CANON
The most restrictive limit permitted by POSIX for the maximum number of bytes in a canonical input line from a terminal device. The value of this constant is 255.

_POSIX_MAX_INPUT
The most restrictive limit permitted by POSIX for the maximum number of bytes in a terminal device input queue (or typeahead buffer). See section Input Modes. The value of this constant is 255.

_POSIX_NAME_MAX
The most restrictive limit permitted by POSIX for the maximum number of bytes in a file name component. The value of this constant is 14.

_POSIX_PATH_MAX
The most restrictive limit permitted by POSIX for the maximum number of bytes in a file name. The value of this constant is 255.

_POSIX_PIPE_BUF
The most restrictive limit permitted by POSIX for the maximum number of bytes that can be written atomically to a pipe. The value of this constant is 512.

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