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coreutils/src/uu/tail
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Jeffrey Finkelstein bc9db289e8 head: add abstractions for "all but last n lines" 
Add some abstractions to simplify the `rbuf_but_last_n_lines()`
function, which implements the "take all but the last `n` lines"
functionality of the `head` program. This commit adds

- `RingBuffer`, a fixed-size ring buffer,
- `ZLines`, an iterator over zero-terminated "lines",
- `TakeAllBut`, an iterator over all but the last `n` elements of an
  iterator.

These three together make the implementation of
`rbuf_but_last_n_lines()` concise.
2021-05-22 23:56:48 -04:00
..
src head: add abstractions for "all but last n lines" 2021-05-22 23:56:48 -04:00
Cargo.toml head: add abstractions for "all but last n lines" 2021-05-22 23:56:48 -04:00
README.md change ~ make all sub-crates independent 2020-05-29 22:59:40 -05:00

README.md

Notes / ToDO

  • Rudimentary tail implementation.

Missing features:

Flags with features

  • --max-unchanged-stats : with --follow=name, reopen a FILE which has not changed size after N (default 5) iterations to see if it has been unlinked or renamed (this is the usual case of rotated log files). With inotify, this option is rarely useful.
  • --retry : keep trying to open a file even when it is or becomes inaccessible; useful when follow‐ing by name, i.e., with --follow=name

Others

  • The current implementation does not handle - as an alias for stdin.

Possible optimizations:

  • Don't read the whole file if not using -f and input is regular file. Read in chunks from the end going backwards, reading each individual chunk forward.