Monday, June 3, 2013

Check Network Speed in Linux                                                        Find Command examples

This article is part of a unix shell scripting tutorial. We must know liitle things like below while writing shell scripts in linux.

Sometimes, we are not able to delete files from directory in Linux. There are many reasons due to which we can’t delete that files as I have given example. Below filename which I have mentioned, its name starts with – that’s why we can’t delete it directly.

You can see just list of files before issue.

root@hello:~/test/hello# ls
a.sh  a.txt  file2  module  test.html  -unable.txt
root@hello:~/test/hello#

I am creating file which will not delete by normal rm command.

root@hello:~/test/hello# cat > -unable.txt
Hello
How are you
root@hello:~/test/hello#
root@hello:~/test/hello# ls
a.sh  a.txt  file2  module  test.html  -unable.txt

rm command facing the issue while deleting that file. We are getting errors.

root@hello:~/test/hello# rm "-unable.txt"
rm: invalid option -- 'u'
Try `rm ./-unable.txt' to remove the file `-unable.txt'.
Try `rm --help' for more information.
root@hello:~/test/hello# rm -rf "-unable.txt"
rm: invalid option -- 'u'
Try `rm ./-unable.txt' to remove the file `-unable.txt'.
Try `rm --help' for more information.
root@hello:~/test/hello#

There is only one way to resolve this issue is that check inode for that file by ls command with –i option. It will give us inode number in first column for that file.

root@hello:~/test/hello# ls -lrti
total 100
5770436 -rw-r--r-- 1 root root 80878 2012-11-03 18:00 test.html
5770345 -rw-r--r-- 1 root root    45 2012-11-05 21:59 file2
5770346 drwxr-xr-x 3 root root  4096 2012-11-05 22:35 module
5770437 -rw-r--r-- 1 root root    11 2012-11-09 16:50 a.txt
5770440 -rw-r--r-- 1 root root   128 2012-11-09 16:50 a.sh
5770079 -rw-r--r-- 1 root root    19 2013-06-03 22:04 -unable.txt
root@hello:~/test/hello#

Use above inode number in find command to search file and delete it by using rm command inside the –exec option. Finally, we have successfully deleted that file.

root@hello:~/test/hello# find . -inum 5770079 -exec rm -rf {} \;
root@hello:~/test/hello# ls
a.sh  a.txt  file2  module  test.html
root@hello:~/test/hello#


This case not belong to only the file names whose name starts with – character but also in some other cases like- if file not created properly then we can’t delete it etc. If you are not able to delete files then just use this trick, it will be helpful for all cases.


Useful tricks of Sed Command in Linux                                               Advanced Sed Comamnd examples
Posted by Machindra Dharmadhikari On 6/03/2013 09:40:00 PM 2 comments READ FULL POST
Netstat Command in Linux                                                               vmstat Command in Linux

It is very easy to check local network speed in Windows but if you have putty access to Linux machine then we are facing issues to check the network speed. There are some tools are available to check network speed iin Linux but it is not possible to install this tools on client machine or our secured machine.

Network speed in linux is depend on the Ethernet card or network interface card which you are using for this machine. Might be there are multiple Ethernet cards already configured, we can check network speed for each separately.

Generally, Ethernet cards are configured. If we see the the output of below command then we will get all NICs.

root@hello:~# ifconfig -a
eth0   Link encap:EthernetHWaddr 1c:6f:65:0b:00:eb
          inet addr:10.136.25.42  Bcast:10.136.25.255  Mask:255.255.255.0
          inet6 addr: fe80::1e6f:65ff:fe0b:eb/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1133376 errors:0 dropped:0 overruns:0 frame:0
          TX packets:34516 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:11234117 (113.8 MB)  TX bytes:9056744 (9.0 MB)
          Interrupt:16 Memory:fc500000-fc520000

lo       Link encap:Local Loopback     
          inet addr:127.0.0.1  Mask:255.255.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:20442 errors:0 dropped:0 overruns:0 frame:0
          TX packets:20442 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:2356951 (2.3 MB)  TX bytes:2356951 (2.3 MB)
root@hello:~#

If we see in above output, there are two cards configured. But eth0 is the main. So we need to check network speed for it only.

For Ethernet card,

root@hello:~# ethtool eth0 | less

If this command is not found then go for below command

root@hello:~# dmesg  | grep -i duplex
[   16.773492] e100e: eth0 NIC Link is Up 100 Mbps Full Duplex, Flow Control: None
root@hello:~#

Above command will be helpful to check system is half duplex or full duplex. Dmesg command gives lots of information but it is not that much of useful for us just grep needed information.

                We can check network speed of wireless card and chipset information.

                root@hello:~#lspci | grep -i wireless

                To test internet connection speed from the console over ssh command line, we need to install lftp and iperf packages. They are easily available. We can download rpm of them or install it from yum repository.

After installation, download or upload data by lftp, pget command or check network speed between two IPs by iperf command.


I got some useful information regarding this topic on one site. Please go through it.

Check CPU usage in Linux                                                                usermod command in Linux
Posted by Machindra Dharmadhikari On 6/03/2013 08:38:00 PM 9 comments READ FULL POST
Not able to delete files in Linux                                               Find command with mtime and atime options

Find command in linux is most important for linux administrators as well as shell script developers. It is really very fast in execution speed and it is useful because of availability of wide variety options with find command.

Find has many options available like ctime i.e. creation time, type – type of file, newer – compare files and decide, it is newer or older as compared to one file, inum- inode number.
Examples:
  • Search files by inode numbers with find command: find inum
root@hello:~/ctier/examples# find . -inum 5770071
./README.txt
root@hello:~/ctier/examples#
  •  Search files newer as compared to given file: find newer
root@hello:~/ctier/examples# find . -type f -newer filename
root@hello:~/ctier/examples# find . -type f -newer README.txt

Newer option helpful to get new files as compared to given file timestamp.
  • Search files older as compared to given file: find newer
root@hello:~/ctier/examples# find . -type f !-newer README.txt

To reverse the output of 2nd example, we need to put !mark before the –newer option. It will negate the meaning of command after the mark.
  •  Search files by uid: find uid
root@hello:~#find . -type f -uidNumeric USERID
root@hello:~#find . -type f -uid 1002

  •  Search files whose creation time is older than 30 days

root@hello:~#find . -type f -ctime +30
  •  Search files whose creation time is within last 30 days

root@hello:~#find . -type f -ctime -30
  •  Search log files whose creation time is older than 30 days and delete it

In this case, we need to search files whose creation time is older than 30 days and need to provide this list of files to the rm command with the help of –exec option. We can run any file manipulation command after exec option e.g. ls –lrt, cat, wc etc.

root@hello:~#find . -type f -name "*.log" -ctime +30 -exec rm -rf {} \;


If you need more examples or facing issues with some option then please write us at linuxconcepts@gmail.com.

How to install Wine Application                                              How to install cygwin and configure

Posted by Machindra Dharmadhikari On 6/03/2013 08:30:00 PM No comments READ FULL POST
Find command is most powerful command in linux to find files as per our criteria. It is used  not only to search files but also to run different commands on those files. Mostly we are searching files by modification time or access time of that file. So, in this article, we will search files by this two parameters only. We will see mtime and atime in detail with examples.
  • To find files who accessed in last 7 days

To find files whose access time is newer i.e. in last 7 days only. Then we can search those files by following command.

root@hello:~/ctier/examples# find . -type f -mtime -7

This command will be helpful to get only files i.e. type option will help to get files or directories if you put d instead of f then it will search for directories. And mtime i.e. modification time should be last 7 days only then it should be -7 and if you want to do reverse i.e. you need all files whose modification time is 7 days before i.e. do not display the files whose modification time is last 7 days then use +7.

mtime option we can use with  multiple find commands option like –newer, -type, -name, -depth etc.

Examples:
  •  To find files whose access time is within last 7 days only


root@hello:~/ctier/examples# find . -type f -atime -7
  •     To search files whose access time is more than 15 days older


root@hello:~/ctier/examples# find . -type f -atime +15
  •  To search files whose modification time is within last 7 days and till the 3 depth of directory


root@hello:~/ctier/examples# find . –maxdepth 3 -type f  –mtime -7
  •  To search files whose modification time is last 30 days ok but access time should be within last 2 days only


root@hello:~/ctier/examples# find . –maxdepth 3 -type f  –mtime-30 –atime 2

- maxdepth option is available but instead of it, many times we need to use - depth option and it varies from OS to OS.


Find atime and find mtime are two mainly used options with find command. If you need more information or having some doubts regarding this then please write us at: linuxconcepts@gmail.com

Difference between Soft link and Hard link                                 Groupadd/Groupdel Command 
Posted by Machindra Dharmadhikari On 6/03/2013 08:21:00 PM 1 comment READ FULL POST
  • RSS
  • Delicious
  • Digg
  • Facebook
  • Twitter
  • Linkedin
  • Youtube

    Chitika Ads 2

    Histat

    About

    Enter your email address:

    Delivered by FeedBurner