linux tail command — output the last part of files.
Print the last 10 lines of each FILE to standard output. With more than one FILE, precede each with a header giving the file name.
The linux tail command corresponds to the linux head command.
tail [OPTION]... [FILE]...
- -c, –bytes=[+]NUM
output the last NUM bytes; or use -c +NUM to output starting with byte NUM of each file
-f option causes tail to not stop when end of file is reached, but rather to wait for additional data to be appended to the input.
- -n, –lines=[+]NUM
output the last NUM lines.
with -f, terminate after process ID, PID dies
- -q, –quiet, –silent
never output headers giving file names
keep trying to open a file if it is inaccessible
- -s, –sleep-interval=N
with -f, sleep for approximately N seconds (default 1.0) between iterations; with inotify and –pid=P, check process P at least once every N seconds
- -v, –verbose
always output headers giving file names
- -z, –zero-terminated
line delimiter is NUL, not newline
linux tail examples
Display the last 10 lines of the file
In the following example, we will use tail to display the last 10 lines of the file.
➜ ~ tail /var/log/dmesg
Display the last 3 lines of file content
➜ ~ tail -3 /var/log/dmesg
Tail skip first N lines
from line 20 to the end of the file:
➜ ~ tail +20 /var/log/dmesg
To monitor the write growth of log files
In the following example, we will use the tail command -f option to monitor file changes in real time; As the file content increases, the output is in real time.
➜ ~ tail -f /var/log/dmesg
use tail with pipes(|)
Display the last 2 lines of the first 10 lines of the file dmesg
➜ ~ head -10 /var/log/dmesg | tail -2