Using The Tail Command
How to used the tail command in unix?
I want to use tail -f with sleep and number of lines, to display
at a time.
I am using:
tail -f -s 20 -n 5 filename.
This is displaying correct result for 1st time, but as tail -f is
appending, I am not able to view 5 lines.
You need to put it in an infinite loop and not use the -f option. Try
this, using the syslog file as an example:
tail -n 5 /usr/adm/syslog
Delivers the last part of the file.
tail [+ number] [-l] [-b] [-c] [-r] [-f] [-c number | -n number] [file]
This option is only recognized if it is specified first. COUNT is a
decimal number optionally followed by a size letter (`b', `k', `m') as
in `-c', or `l' to mean count by lines, or other option letters (`cfqv').
Units of lines.
Units of blocks.
Units of bytes.
Copies lines from the specified starting point in the file in reverse
order. The default for r is to print the entire file in reverse order.
If the input-file is not a pipe, the program will not terminate after
the line of the input-file has been copied, but will enter an endless loop,
wherein it sleeps for a second and then attempts to read and copy further
records from the input-file. Thus it may be used to monitor the growth
of a file that is being written by some other process.
The number option-argument must be a decimal integer whose sign affects
the location in the file, measured in bytes, to begin the copying:
+ Copying starts relative to the beginning of the file.
- Copying starts relative to the end of the file.
none Copying starts relative to the end of the file.
The origin for counting is 1; that is, -c+1 represents the first byte
of the file, -c-1 the last.
Equivalent to -c number, except the starting location in the file is
measured in lines instead of bytes. The origin for counting is 1; that
is, -n+1 represents the first line of the file, -n-1 the last.
Name of the file you wish to display
The above example would list the last 10 (default) lines of the file
tail myfile.txt -n 100
The above example would list the last 100 lines in the file myfile.txt.
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