57 lines
2.1 KiB
Markdown
57 lines
2.1 KiB
Markdown
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# The `tail` command
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The `tail` command prints the last ten lines of a file.
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Example:
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```
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tail filename.txt
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```
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Syntax:
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```
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tail [OPTION] [FILENAME]
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```
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### Get a specific number of lines with `tail`:
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Use the `-n` option with a number(should be an integer) of lines to display.
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Example:
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```
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tail -n 10 foo.txt
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```
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This command will display the last ten lines of the file `foo.txt`.
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### Refresh the output on any new entry in a file
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It is possible to let tail output any new line added to the file you are looking into. So, if a new line is written to the file, it will immediately be shown in your output. This can be done using the `--follow` or `-f` option. This is especially useful for monitoring log files.
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Example:
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```
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tail -f foo.txt
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```
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Syntax:
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```
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tail -n <number> foo.txt
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```
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### Additional Flags and their Functionalities
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|**Short Flag** |**Long Flag** |**Description** |
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|:---|:---|:---|
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|`-c`|`--bytes=[+]NUM`|Output the last NUM bytes;<br> or use -c +NUM to <br>output starting with byte NUM of each file|
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|`-f`|<code>--follow[={name|descriptor}]</code>|Output appended data as the file grows;<br>an absent option argument means 'descriptor'|
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|`-F`||Same as --follow=name --retry|
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|`-n`|`--lines=[+]NUM`|Output the last NUM lines, instead of the last 10;<br>or use -n +NUM to output starting with line NUM|
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||`--max-unchanged-stats=N`|with --follow=name, reopen a FILE which has not<br>changed size after N (default 5) iterations<br>to see if it has been unlinked or rename<br>(this is the usual case of rotated log files);<br>with inotify, this option is rarely useful|
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||`--pid=PID`|with -f, terminate after process ID, PID dies|
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|`-q`|`--quiet, --silent`|Never output headers giving file names|
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|``|`--retry`|keep trying to open a file if it is inaccessible|
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|`-s`|`--sleep-interval=N`|With -f, sleep for approximately N seconds<br>(default 1.0) between iterations;<br>with inotify and --pid=P, check process P at<br>least once every N seconds|
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|`-v`|`--verbose`|Always output headers giving file names|
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|`-z`|`--zero-terminated`|Line delimiter is NUL, not newline|
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||`--help`|Display this help and exit|
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||`--version`|Output version information and exit|
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