Display the last part of a file

tail [-f | -r] [-b number | -c number | -n number | -number] [file ...] 

The tail utility displays the contents of file or, by default, its standard input, to the standard output.

The display begins at a byte, line, or 512-byte block location in the input. Numbers having a leading plus (‘+’) sign are relative to the beginning of the input, for example, -c +2 starts the display at the second byte of the input. Numbers having a leading minus (‘-’) sign or no explicit sign are relative to the end of the input, for example, -n 2 displays the last two lines of the input. The default starting location is -n 10, or the last 10 lines of the input.

The options are as follows:

-b number
The location is number 512-byte blocks.

-c number
The location is number bytes.

-n number | -number
The location is number lines.

-f
Do not stop when end-of-file is reached, but rather to wait for additional data to be appended to the input. If the file is replaced (i.e., the inode number changes), tail will reopen the file and continue. If the file is truncated, tail will reset its position to the beginning. This makes tail more useful for watching log files that may get rotated. The -f option is ignored if the standard input is a pipe, but not if it is a FIFO.

-r
The -r option causes the input to be displayed in reverse order, by line. Additionally, this option changes the meaning of the -b, -c, and -n options. When the -r option is specified, these options specify the number of bytes, lines or 512-byte blocks to display, instead of the bytes, lines, or blocks from the beginning or end of the input from which to begin the display. The default for the -r option is to display all of the input.

If more than a single file is specified, each file is preceded by a header consisting of the string ‘‘=⇒ XXX ⇐=’’ where ‘‘XXX’’ is the name of the file.

The tail utility exits 0 on success or >0 if an error occurred.

To display the last 500 lines of the file foo:

$ tail -500 foo 
Keep /var/log/messages open, displaying to the standard output anything appended to the file: 
$ tail -f /var/log/messages