One Linux command per day: Tail command

Tag: Data does not display option specifies the TTL process ID int byte file

The tail command writes the file to standard output starting at the specified point. Using the-f option of the tail command makes it easy to see the log files that are being changed, TAIL-F filename will display the most up-to-date contents of the filename on the screen, and not only refresh, so you can view the latest file content.

1. command format;

tail[necessary parameters [selection parameters] [file]

2. Command function:

Used to display the content at the end of the specified file, and is processed as input when the file is not specified. Common view log files.

3. Command parameters:

-F Loop Read

-Q does not display processing information

-V displays detailed processing information

Number of-c< > bytes displayed

-n< lines > Display rows

--pid=pid is shared with-F, which means that the process ends after the id,pid dies.

-Q,--quiet,--silent never output the header of the file name

-S,--sleep-interval=s is combined with-F, which means sleep s seconds at each repetition interval

4. Usage examples:

Example 1: Displaying the end of a file

Command:

Tail-n 5 Log2014.log

Output:

[Email protected] test]# tail-n 5 Log2014.log

2014-09

2014-10

2014-11

2014-12

==============================[[email protected] test]#

Description

Displays the last 5 lines of the file

Example 2: Looping through the contents of a file

Command:

Tail-f Test.log

Output:

[Email protected] ~]# ping 192.168.120.204 > Test.log &

[1] 11891[[email protected] ~]# tail-f Test.log

PING 192.168.120.204 (192.168.120.204) bytes of data.

Bytes from 192.168.120.204:icmp_seq=1 ttl=64 time=0.038 ms

Bytes from 192.168.120.204:icmp_seq=2 ttl=64 time=0.036 ms

Bytes from 192.168.120.204:icmp_seq=3 ttl=64 time=0.033 ms

Bytes from 192.168.120.204:icmp_seq=4 ttl=64 time=0.027 ms

Bytes from 192.168.120.204:icmp_seq=5 ttl=64 time=0.032 ms

Bytes from 192.168.120.204:icmp_seq=6 ttl=64 time=0.026 ms

Bytes from 192.168.120.204:icmp_seq=7 ttl=64 time=0.030 ms

Bytes from 192.168.120.204:icmp_seq=8 ttl=64 time=0.029 ms

Bytes from 192.168.120.204:icmp_seq=9 ttl=64 time=0.044 ms

Bytes from 192.168.120.204:icmp_seq=10 ttl=64 time=0.033 ms

Bytes from 192.168.120.204:icmp_seq=11 ttl=64 time=0.027 ms

[Email protected] ~]#

Description

Ping 192.168.120.204 > Test.log &//Ping remote host in background. and output files to Test.log; This practice also allows for more than one file to monitor. Use CTRL + C to terminate.

Example 3: Displaying a file starting from line 5th

Command:

Tail-n +5 Log2014.log

Output:

[email protected] test]# cat Log2014.log

2014-01

2014-02

2014-03

2014-04

2014-05

2014-06

2014-07

2014-08

2014-09

2014-10

2014-11

2014-12

==============================

[Email protected] test]# tail-n +5 log2014.log

2014-05

2014-06

2014-07

2014-08

2014-09

2014-10

2014-11

2014-12

==============================

One Linux command per day: Tail command