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| <h3 class="section">31.8 Minimum Values for File System Limits</h3> |
| |
| <p>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. In most cases GNU systems do not |
| have these strict limitations. The actual limit should be requested if |
| necessary. |
| |
| <dl> |
| <!-- limits.h --> |
| <!-- POSIX.1 --> |
| <dt><code>_POSIX_LINK_MAX</code><dd>The most restrictive limit permitted by POSIX for the maximum value of a |
| file's link count. The value of this constant is <code>8</code>; thus, you |
| can always make up to eight names for a file without running into a |
| system limit. |
| |
| <!-- limits.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>_POSIX_MAX_CANON</code><dd>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 <code>255</code>. |
| |
| <!-- limits.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>_POSIX_MAX_INPUT</code><dd>The most restrictive limit permitted by POSIX for the maximum number of |
| bytes in a terminal device input queue (or typeahead buffer). |
| See <a href="Input-Modes.html#Input-Modes">Input Modes</a>. The value of this constant is <code>255</code>. |
| |
| <!-- limits.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>_POSIX_NAME_MAX</code><dd>The most restrictive limit permitted by POSIX for the maximum number of |
| bytes in a file name component. The value of this constant is |
| <code>14</code>. |
| |
| <!-- limits.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>_POSIX_PATH_MAX</code><dd>The most restrictive limit permitted by POSIX for the maximum number of |
| bytes in a file name. The value of this constant is <code>256</code>. |
| |
| <!-- limits.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>_POSIX_PIPE_BUF</code><dd>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 <code>512</code>. |
| |
| <!-- limits.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>SYMLINK_MAX</code><dd>Maximum number of bytes in a symbolic link. |
| |
| <!-- limits.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>POSIX_REC_INCR_XFER_SIZE</code><dd>Recommended increment for file transfer sizes between the |
| <code>POSIX_REC_MIN_XFER_SIZE</code> and <code>POSIX_REC_MAX_XFER_SIZE</code> |
| values. |
| |
| <!-- limits.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>POSIX_REC_MAX_XFER_SIZE</code><dd>Maximum recommended file transfer size. |
| |
| <!-- limits.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>POSIX_REC_MIN_XFER_SIZE</code><dd>Minimum recommended file transfer size. |
| |
| <!-- limits.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>POSIX_REC_XFER_ALIGN</code><dd>Recommended file transfer buffer alignment. |
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