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Tail command syntax

The code is as follows:

Tail [- f] [- c Number |-n Number |-m Number |-b Number |-k Number] [File]

Parameter explanation:

-f this parameter is used to monitor the growth of File files.

-c Number reads the specified file from the Number byte location

-n Number reads the specified file from the Number line location.

-m Number reads the specified file from the Number multi-byte character location, for example, your file assumes that it includes Chinese characters, and if you specify the-c parameter, it may cause truncation, but using-m will avoid the problem.

-b Number reads the specified file from the 512-byte block location represented by Number.

-k Number reads the specified file from the 1KB block location represented by Number.

File specifies the target file name of the operation

In all the above commands, number is involved. If it is not specified, 10 lines are displayed by default. Number can be preceded by a plus or minus sign, indicating whether the offset is calculated from the top or from the tail.

Tail runnable files are generally below / usr/bin/.

1. Command format

Tail [necessary parameters] [Select parameters] [File]

2. Command function:

Used to display the end of the specified file, and when no file is specified, it is processed as input information. Commonly used to view log files.

3. Command parameters:

-f loop read

-Q does not display processing information

-v displays detailed processing information

Number of bytes displayed by-c

-n shows the number of rows

-- pid=PID is used with-f to indicate that it ends after the process ID,PID dies.

-Q,-- quiet,-- silent never outputs the first part of the given file name

-s,-- sleep-interval=S is used with-f to indicate dormancy for S seconds at intervals of each iteration.

4. Use an example:

Example 1: displays the content at the end of the file

Command:

Tail-n 5 log2014.log

Output:

[root@localhost test] # tail-n 5 log2014.log

2014-09

2014-10

2014-11

2014-12

= = [root@localhost test] #

Description:

Show the last five lines of the file

Example 2: loop through the contents of the file

Command:

Tail-f test.log

Output:

[root@localhost ~] # ping 192.168.120.204 > test.log &

[1] 11891 [root@localhost ~] # tail-f test.log

PING 192.168.120.204 (192.168.120.204) 56 (84) bytes of data.

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

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

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

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

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

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

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

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

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

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

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

[root@localhost ~] #

Description:

Ping 192.168.120.204 > test.log & / / ping the remote host in the background. The practice of outputting files to test.log; is also used for more than one file monitoring. Terminate with Ctrl+c.

Example 3: display the file from line 5

Command:

Tail-n + 5 log2014.log

Output:

[root@localhost 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

= =

[root@localhost test] # tail-n + 5 log2014.log

2014-05

2014-06

2014-07

2014-08

2014-09

2014-10

2014-11

2014-12

= =

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