A Place To Learn Software Technologies: Linux Commands

Showing posts with label Linux Commands. Show all posts

Linux Command To Rename The Multiple Files

[sujin@localhost blog]$ ls -l
total 0
-rw-rw-r--. 1 sujin sujin 0 Oct 19 13:12 centos6file1
-rw-rw-r--. 1 sujin sujin 0 Oct 19 13:12 centos6file2
-rw-rw-r--. 1 sujin sujin 0 Oct 19 13:12 centos6file3
-rw-rw-r--. 1 sujin sujin 0 Oct 19 13:12 centos6file4
-rw-rw-r--. 1 sujin sujin 0 Oct 19 13:12 centos6file5
-rw-rw-r--. 1 sujin sujin 0 Oct 19 13:14 centos6file6
-rw-rw-r--. 1 sujin sujin 0 Oct 19 13:14 centos6file7
-rw-rw-r--. 1 sujin sujin 0 Oct 19 13:14 centos6file8

From the above list of files i want change all the filename starting with centos6 to centos7. I mean file centos6file2 changed to centos7file2.

It is bit time consuming using mv command to change it one by one. Persong who using mv command for do this not a good linux user.

By using a linux command called rename we can achieve this.

rename centos6 centos7 centos6*

After applying above command file name list would be like below.

[sujin@localhost blog]$ rename centos6 centos7 centos6*

[sujin@localhost blog]$

[sujin@localhost blog]$ ls -l

total 0

-rw-rw-r--. 1 sujin sujin 0 Oct 19 13:12 centos7file1

-rw-rw-r--. 1 sujin sujin 0 Oct 19 13:12 centos7file2

-rw-rw-r--. 1 sujin sujin 0 Oct 19 13:12 centos7file3

-rw-rw-r--. 1 sujin sujin 0 Oct 19 13:12 centos7file4

-rw-rw-r--. 1 sujin sujin 0 Oct 19 13:12 centos7file5

-rw-rw-r--. 1 sujin sujin 0 Oct 19 13:14 centos7file6

-rw-rw-r--. 1 sujin sujin 0 Oct 19 13:14 centos7file7

-rw-rw-r--. 1 sujin sujin 0 Oct 19 13:14 centos7file8

!!!

Operating System Used : Fedora release 20 (Heisenbug)

Linux command to get page size

By using getconf command we can get the size of Virtual Memory page in bytes.

[root@host-7-41 fedo]# getconf PAGESIZE
4096

Here PAGESIZE is the argument passed to the getconf to get virtual memory page size. It gives the output as 4096 bytes.

!!!

Operating System Used : CentOS release 6.5 (Final)

Linux Command to Check OS Architecture is 32 or 64 bit

Recent days all the major Linux operating system support two type of architecture. Those are 32 bit architecture and 64 bit architecture. There is no explicit option available to know which type of architecture you are working. Operating System GUI has option to see this facility even in LINUX knowing everything from Command line has the advantage. Below commands help you to find the Linux operating system architecture. Here i used CentOS release 6.3 to make this article.

1. uname -a -- This command will display the kernel architecture whether it 32 bit or 64 bit. Output of this command vary depends on the hardware architecture.
For Intel 32 bit - i686 or x86
For Intel 64 bit - x86-64

[fedo@localhost ~]$ uname -m
x86_64

2. getconf LONG_BIT -- We can use this command also to get the architecture

[fedo@localhost ~]$ getconf LONG_BIT
64

3. arch -- This command also help to find the architecture

[fedo@localhost workspace]$ arch
x86_64

4. lscpu -- you can get the all the details about OS and CPU support using this command

[fedo@localhost ~]$ lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 1
On-line CPU(s) list: 0
Thread(s) per core: 1
Core(s) per socket: 1
CPU socket(s): 1
NUMA node(s): 1
Vendor ID: GenuineIntel
CPU family: 6
Model: 58
Stepping: 9
CPU MHz: 3192.839
BogoMIPS: 6385.67
L1d cache: 32K
L1i cache: 32K
L2 cache: 256K
L3 cache: 3072K
NUMA node0 CPU(s): 0

5. If you want to get OS architecture through C/C++ program you can use below code

Program:

#include <stdio.h>
int main()
{
printf("%d bit \n", __WORDSIZE);
return 0;
}

Output:

64 bit

Check disk space in linux using df command

Linux Version & distribution used for this article
[root@localhost workspace]# uname -sr
Linux 2.6.32-279.el6.x86_64

[root@localhost workspace]# cat /etc/redhat-release

CentOS release 6.3 (Final)

1. df -- It display available file system details like device name, total size, used space and available space

[root@localhost workspace]# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/mapper/vg_fedo-lv_root
18133780 3579124 14370472 20% /
tmpfs 247288 420 246868 1% /dev/shm
/dev/sda1 495844 33920 436324 8% /boot

2. a -- include dummy filesystem

[root@localhost workspace]# df -a
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/mapper/vg_fedo-lv_root
18133780 3591168 14358428 21% /
proc 0 0 0 - /proc
sysfs 0 0 0 - /sys
devpts 0 0 0 - /dev/pts
tmpfs 247288 420 246868 1% /dev/shm
/dev/sda1 495844 33920 436324 8% /boot
none 0 0 0 - /proc/sys/fs/binfmt_misc
vmware-vmblock 0 0 0 - /var/run/vmblock-fuse
sunrpc 0 0 0 - /var/lib/nfs/rpc_pipefs

3. h -- human readable format. It will display size format as GB, MB, KB

[root@localhost workspace]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_fedo-lv_root
18G 3.5G 14G 21% /
tmpfs 242M 420K 242M 1% /dev/shm
/dev/sda1 485M 34M 427M 8% /boot

4. df -h / -- Display only certain mount point

[root@localhost workspace]# df -h /
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_fedo-lv_root
18G 3.7G 14G 22% /

[root@localhost workspace]# df -h /boot
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 485M 34M 427M 8% /boot

5. df -B 512 -- we can change the size of block its displaying. Below example each block has 512 bytes

[root@localhost workspace]# df -B 512
Filesystem 512B-blocks Used Available Use% Mounted on
/dev/mapper/vg_fedo-lv_root
36267560 7636832 28262360 22% /
tmpfs 494576 864 493712 1% /dev/shm
/dev/sda1 991688 67840 872648 8% /boot

6. df --block-size=512k -- display block in KB format. here it will show each block is 512kb

[root@localhost workspace]# df --block-size=512k
Filesystem 512K-blocks Used Available Use% Mounted on
/dev/mapper/vg_fedo-lv_root
35418 7458 27600 22% /
tmpfs 483 1 483 1% /dev/shm
/dev/sda1 969 67 853 8% /boot

7. m -- display block size in MB

[root@localhost workspace]# df -m
Filesystem 1M-blocks Used Available Use% Mounted on
/dev/mapper/vg_fedo-lv_root
17709 3729 13800 22% /
tmpfs 242 1 242 1% /dev/shm
/dev/sda1 485 34 427 8% /boot

8. --total -- display the grand total

[root@localhost workspace]# df --total
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/mapper/vg_fedo-lv_root
18133780 3818416 14131180 22% /
tmpfs 247288 432 246856 1% /dev/shm
/dev/sda1 495844 33920 436324 8% /boot
total 18876912 3852768 14814360 21%

9. i -- list inode information instead of block usage

[root@localhost workspace]# df -i
Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/mapper/vg_fedo-lv_root
1155072 138135 1016937 12% /
tmpfs 61822 7 61815 1% /dev/shm
/dev/sda1 128016 40 127976 1% /boot

10. T -- It will display additionaly filesystem type like ext3, ext4.

[root@localhost workspace]# df -T
Filesystem Type 1K-blocks Used Available Use% Mounted on
/dev/mapper/vg_fedo-lv_root
ext4 18133780 3818420 14131176 22% /
tmpfs tmpfs 247288 432 246856 1% /dev/shm
/dev/sda1 ext4 495844 33920 436324 8% /boot

11. t -- helps to display specific type of file system

[root@localhost workspace]# df -Tt ext4
Filesystem Type 1K-blocks Used Available Use% Mounted on
/dev/mapper/vg_fedo-lv_root
ext4 18133780 3818412 14131184 22% /
/dev/sda1 ext4 495844 33920 436324 8% /boot

12. x -- exclude specific type of file system

[root@localhost workspace]# df -Tx ext4
Filesystem Type 1K-blocks Used Available Use% Mounted on
tmpfs tmpfs 247288 432 246856 1% /dev/shm

13. df --help -- to get df command help information

ENJOY & HAVE FUN WITH LINUX!!!!