diff & ac Command Example

Diff Command Examples

diff command compares two different files and reports the difference. The output is very cryptic and not straight forward to read.

Syntax: 

#diff [options] file1 file2

option  :

-w in the diff command will ignore the white space while performing the comparison. 

[root@desktop17 ~]# cat abc1
network cloud
kr network cloud
hello
[root@desktop17 ~]# cat abc2
network cloud
hi
kr network cloud
hello
[root@desktop17 ~]# diff abc1 abc2
1a2
> hi

[root@desktop17 ~]#  

Duplicate File Changes Patch

Diff and Patch command:- 

* diff output stored in a file is called a "patchfile"

 use  -u for "unified" diff, best in patchfiles

* patch duplicates changes in other files (user with care!)

  use -b to automatically backup changed files.

[root@desktop17 ~]# cat abc1
network cloud

hi 

kr network cloud
hello

[root@desktop17 ~]#cp abc1 abc2
[root@desktop17 ~]# cat abc2
network cloud

hi 

kr network cloud
hello

[root@desktop17 ~]# vim abc2

edit some thing new.

:wq 

[root@desktop17 ~]# diff -u abc1 abc2 
--- abc1    2013-06-14 15:28:46.845938983 +0530
+++ abc2    2013-06-14 15:28:33.439937131 +0530
@@ -1,4 +1,3 @@
 network cloud
-hi
 network cloud
 hello
[root@desktop17 ~]# diff -u abc1 abc2  > /tmp/abc.patch
[root@desktop17 ~]# 
[root@desktop17 ~]# 
[root@desktop17 ~]# patch  -b abc1 /tmp/abc.patch 
patching file abc1
[root@desktop17 ~]# cat abc1
network cloud

hi
kr network cloud
hello
 

 Means Confirm thathave been applied by running diff again.

 You should see no output, indicating that the files are now identical.

Display total connect time of users

Ac command will display the statistics about the user’s connect time.

Connect time for the current logged in user

With the option –d, it will break down the output for the individual days. In this example, I’ve been logged in to the system for more than 6 hours today. On Dec 1st, I was logged in for about 1 hour.

# ac –d

Dec  1  total        1.08
Dec  2  total        0.99
Dec  3  total        3.39
Dec  4  total        4.50
Today   total        6.10

Connect time for all the users

To display connect time for all the users use –p as shown below. Please note that this indicates the cumulative connect time for the individual users.

# ac -p 

        harry                               3.64
        madison                             0.06
        sanjay                              88.17
        nitesh                              105.92
        rakesh                              111.42
        total 309.21

Connect time for a specific user

To get a connect time report for a specific user, execute the following:

# ac -d nitesh

Jul  2  total       12.85
Aug 25  total        5.05
Sep  3  total        1.03
Sep  4  total        5.37
Dec 24  total        8.15
Dec 29  total        1.42
Today   total        2.95