ifconfig - configure a network interface :
The “ifconfig” command with no arguments will display all the active interfaces details. The ifconfig command also used to check the assigned IP address of an server.
ifconfig -a
The following ifconfig command with -a argument will display information of all active or inactive network interfaces on server. It displays the results for eth0, lo.
Linux command to replace a keyword in multiple file :
find . -name '*.exp' | xargs sed -i 's/set_topology/#set_topology/g'
In above example replace set_topology with #set_topology in all .exp files.
How to enable root access on Linux
configure
set system login user root authentication plaintext-password root123
commit
save
How to enable ssh root access on Linux
configure
set service ssh allow-root
commit
save
How to enable telnet root access on Linux
configure
set service telnet allow-root
commit
save
Linux command to find file size
df – show disk usage
du – show directory space usage
free – show memory and swap usage
du -h <filename>
[root@cisco /]# ls -lrt boot/
total 179175
-rwxr-xr-x. 1 root root 3811616 Dec 6 2011 vmlinuz-2.6.32-220.el6.i686
-rw-r--r--. 1 root root 1823458 Dec 6 2011 System.map-2.6.32-220.el6.i686
-rw-r--r--. 1 root root 105744 Dec 6 2011 config-2.6.32-220.el6.i686
-rw-r--r--. 1 root root 168173 Dec 6 2011 symvers-2.6.32-220.el6.i686.gz
-rw-r--r--. 1 root root 3242592 Oct 5 2012 vmlinuz-2.6.32.59-ZebOS7_10_1
-rw-r--r--. 1 root root 1551956 Oct 5 2012 System.map-2.6.32.59-ZebOS7_10_1
drwx------. 2 root root 12288 Dec 3 2012 lost+found
drwxr-xr-x. 3 root root 1024 Dec 3 2012 efi
-rw-r--r--. 1 root root 14733014 Dec 3 2012 initramfs-2.6.32-220.el6.i686.img
-rw-r--r--. 1 root root 77259645 Dec 10 2012 initramfs-2.6.32.59-ZebOS7_10_1.img
-rw-r--r--. 1 root root 3266176 Dec 12 2013 vmlinuz-2.6.32.59-ZebOS7_10_5
-rw-r--r--. 1 root root 1588509 Dec 12 2013 System.map-2.6.32.59-ZebOS7_10_5
-rw-r--r--. 1 root root 75887961 Nov 12 2014 initramfs-2.6.32.59-ZebOS7_10_5.img
drwxr-xr-x. 2 root root 1024 Nov 12 2014 grub
[root@cisco /]# du -h boot/
277K boot/grub
239K boot/efi/EFI/redhat
241K boot/efi/EFI
243K boot/efi
13K boot/lost+found
176M boot/
[root@cisco /]# ls boot/efi/
EFI
[root@cisco /]# ls boot/efi/EFI/
redhat
[root@cisco /]# ls boot/efi/EFI/redhat/
grub.efi
df -h
[root@cisco /]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_vpc1-lv_root
5.8G 5.4G 107M 99% /
tmpfs 187M 0 187M 0% /dev/shm
/dev/sda1 485M 186M 274M 41% /boot
[root@cisco /]# free -m
total used free shared buffers cached
Mem: 372 365 6 0 104 44
-/+ buffers/cache: 216 155
Swap: 1727 0 1727
/proc/meminfo
The next way to check memory usage is to read the /proc/meminfo file. Know that the /proc file system does not contain real files. They are rather virtual files that contain dynamic information about the kernel and the system.
[root@vpc11 /]# cat /proc/meminfo
MemTotal: 381296 kB
MemFree: 7092 kB
Buffers: 107104 kB
Cached: 45316 kB
SwapCached: 164 kB
Active: 94232 kB
Inactive: 114516 kB
Active(anon): 27924 kB
Inactive(anon): 28620 kB
Active(file): 66308 kB
Inactive(file): 85896 kB
Unevictable: 0 kB
Mlocked: 0 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 381296 kB
LowFree: 7092 kB
SwapTotal: 1769464 kB
SwapFree: 1769072 kB
Dirty: 4 kB
Writeback: 0 kB
AnonPages: 56188 kB
Mapped: 13044 kB
Shmem: 216 kB
Slab: 157340 kB
SReclaimable: 114640 kB
SUnreclaim: 42700 kB
KernelStack: 848 kB
PageTables: 1776 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 1960112 kB
Committed_AS: 154048 kB
VmallocTotal: 509956 kB
VmallocUsed: 2916 kB
VmallocChunk: 467140 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB
DirectMap4k: 8180 kB
DirectMap2M: 516096 kB
vmstat
The vmstat command with the s option, lays out the memory usage statistics much like the proc command. Here is an example
[root@vpc11 /]# vmstat -s
381296 total memory
374204 used memory
94248 active memory
114524 inactive memory
7092 free memory
107104 buffer memory
45340 swap cache
1769464 total swap
392 used swap
1769072 free swap
17628 non-nice user cpu ticks
250 nice user cpu ticks
10176 system cpu ticks
52401867 idle cpu ticks
12789 IO-wait cpu ticks
1328 IRQ cpu ticks
398 softirq cpu ticks
0 stolen cpu ticks
820782 pages paged in
1036644 pages paged out
0 pages swapped in
102 pages swapped out
5308293 interrupts
12370350 CPU context switches
1434517884 boot time
29304 forks
top command
The top command is generally used to check memory and cpu usage per process. However it also reports total memory usage and can be used to monitor the total RAM usage. The header on output has the required information. Here is a sample output
top - 12:25:44 up 6 days, 1:44, 3 users, load average: 0.01, 0.02, 0.00
Tasks: 96 total, 1 running, 95 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.0%us, 0.3%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 381296k total, 374452k used, 6844k free, 107128k buffers
Swap: 1769464k total, 392k used, 1769072k free, 45508k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
29044 root 20 0 11532 2612 1612 S 0.3 0.7 0:00.61 nsm
29306 root 20 0 2680 1064 844 R 0.3 0.3 0:00.06 top
1 root 20 0 2892 1240 1064 S 0.0 0.3 0:02.44 init
2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd
3 root 20 0 0 0 0 S 0.0 0.0 0:01.62 ksoftirqd/0
4 root RT 0 0 0 0 S 0.0 0.0 0:00.00 watchdog/0
5 root 20 0 0 0 0 S 0.0 0.0 0:09.07 events/0
grep pattern file Search for pattern in file
[root@cisco ~]# cat /etc/*release
CentOS release 6.2 (Final)
[root@cisco ~]# lsb_release -a
LSB Version: :core-4.0-ia32:core-4.0-noarch:graphics-4.0-ia32:graphics-4.0-noarch:printing-4.0-ia32:printing-4.0-noarch
Distributor ID: CentOS
Description: CentOS release 6.2 (Final)
Release: 6.2
Codename: Final
ps uw -p <pid>
[root@VPC50 ~]# ps -ef | grep netconfd
root 1369 1224 0 16:26 pts/0 00:00:00 netconfd --superuser=root
root 1577 1516 0 16:31 pts/2 00:00:00 grep --color=auto netconfd
[root@VPC50 ~]# ps uw -p 1369
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1369 0.0 0.6 18748 6064 pts/0 S+ 16:26 0:00 netconfd --superuser=root
The “ifconfig” command with no arguments will display all the active interfaces details. The ifconfig command also used to check the assigned IP address of an server.
ifconfig -a
The following ifconfig command with -a argument will display information of all active or inactive network interfaces on server. It displays the results for eth0, lo.
Linux command to replace a keyword in multiple file :
find . -name '*.exp' | xargs sed -i 's/set_topology/#set_topology/g'
In above example replace set_topology with #set_topology in all .exp files.
How to enable root access on Linux
configure
set system login user root authentication plaintext-password root123
commit
save
How to enable ssh root access on Linux
configure
set service ssh allow-root
commit
save
How to enable telnet root access on Linux
configure
set service telnet allow-root
commit
save
Linux command to find file size
df – show disk usage
du – show directory space usage
free – show memory and swap usage
du -h <filename>
[root@cisco /]# ls -lrt boot/
total 179175
-rwxr-xr-x. 1 root root 3811616 Dec 6 2011 vmlinuz-2.6.32-220.el6.i686
-rw-r--r--. 1 root root 1823458 Dec 6 2011 System.map-2.6.32-220.el6.i686
-rw-r--r--. 1 root root 105744 Dec 6 2011 config-2.6.32-220.el6.i686
-rw-r--r--. 1 root root 168173 Dec 6 2011 symvers-2.6.32-220.el6.i686.gz
-rw-r--r--. 1 root root 3242592 Oct 5 2012 vmlinuz-2.6.32.59-ZebOS7_10_1
-rw-r--r--. 1 root root 1551956 Oct 5 2012 System.map-2.6.32.59-ZebOS7_10_1
drwx------. 2 root root 12288 Dec 3 2012 lost+found
drwxr-xr-x. 3 root root 1024 Dec 3 2012 efi
-rw-r--r--. 1 root root 14733014 Dec 3 2012 initramfs-2.6.32-220.el6.i686.img
-rw-r--r--. 1 root root 77259645 Dec 10 2012 initramfs-2.6.32.59-ZebOS7_10_1.img
-rw-r--r--. 1 root root 3266176 Dec 12 2013 vmlinuz-2.6.32.59-ZebOS7_10_5
-rw-r--r--. 1 root root 1588509 Dec 12 2013 System.map-2.6.32.59-ZebOS7_10_5
-rw-r--r--. 1 root root 75887961 Nov 12 2014 initramfs-2.6.32.59-ZebOS7_10_5.img
drwxr-xr-x. 2 root root 1024 Nov 12 2014 grub
[root@cisco /]# du -h boot/
277K boot/grub
239K boot/efi/EFI/redhat
241K boot/efi/EFI
243K boot/efi
13K boot/lost+found
176M boot/
[root@cisco /]# ls boot/efi/
EFI
[root@cisco /]# ls boot/efi/EFI/
redhat
[root@cisco /]# ls boot/efi/EFI/redhat/
grub.efi
df -h
[root@cisco /]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_vpc1-lv_root
5.8G 5.4G 107M 99% /
tmpfs 187M 0 187M 0% /dev/shm
/dev/sda1 485M 186M 274M 41% /boot
[root@cisco /]# free -m
total used free shared buffers cached
Mem: 372 365 6 0 104 44
-/+ buffers/cache: 216 155
Swap: 1727 0 1727
/proc/meminfo
The next way to check memory usage is to read the /proc/meminfo file. Know that the /proc file system does not contain real files. They are rather virtual files that contain dynamic information about the kernel and the system.
[root@vpc11 /]# cat /proc/meminfo
MemTotal: 381296 kB
MemFree: 7092 kB
Buffers: 107104 kB
Cached: 45316 kB
SwapCached: 164 kB
Active: 94232 kB
Inactive: 114516 kB
Active(anon): 27924 kB
Inactive(anon): 28620 kB
Active(file): 66308 kB
Inactive(file): 85896 kB
Unevictable: 0 kB
Mlocked: 0 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 381296 kB
LowFree: 7092 kB
SwapTotal: 1769464 kB
SwapFree: 1769072 kB
Dirty: 4 kB
Writeback: 0 kB
AnonPages: 56188 kB
Mapped: 13044 kB
Shmem: 216 kB
Slab: 157340 kB
SReclaimable: 114640 kB
SUnreclaim: 42700 kB
KernelStack: 848 kB
PageTables: 1776 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 1960112 kB
Committed_AS: 154048 kB
VmallocTotal: 509956 kB
VmallocUsed: 2916 kB
VmallocChunk: 467140 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB
DirectMap4k: 8180 kB
DirectMap2M: 516096 kB
vmstat
The vmstat command with the s option, lays out the memory usage statistics much like the proc command. Here is an example
[root@vpc11 /]# vmstat -s
381296 total memory
374204 used memory
94248 active memory
114524 inactive memory
7092 free memory
107104 buffer memory
45340 swap cache
1769464 total swap
392 used swap
1769072 free swap
17628 non-nice user cpu ticks
250 nice user cpu ticks
10176 system cpu ticks
52401867 idle cpu ticks
12789 IO-wait cpu ticks
1328 IRQ cpu ticks
398 softirq cpu ticks
0 stolen cpu ticks
820782 pages paged in
1036644 pages paged out
0 pages swapped in
102 pages swapped out
5308293 interrupts
12370350 CPU context switches
1434517884 boot time
29304 forks
top command
The top command is generally used to check memory and cpu usage per process. However it also reports total memory usage and can be used to monitor the total RAM usage. The header on output has the required information. Here is a sample output
top - 12:25:44 up 6 days, 1:44, 3 users, load average: 0.01, 0.02, 0.00
Tasks: 96 total, 1 running, 95 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.0%us, 0.3%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 381296k total, 374452k used, 6844k free, 107128k buffers
Swap: 1769464k total, 392k used, 1769072k free, 45508k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
29044 root 20 0 11532 2612 1612 S 0.3 0.7 0:00.61 nsm
29306 root 20 0 2680 1064 844 R 0.3 0.3 0:00.06 top
1 root 20 0 2892 1240 1064 S 0.0 0.3 0:02.44 init
2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd
3 root 20 0 0 0 0 S 0.0 0.0 0:01.62 ksoftirqd/0
4 root RT 0 0 0 0 S 0.0 0.0 0:00.00 watchdog/0
5 root 20 0 0 0 0 S 0.0 0.0 0:09.07 events/0
grep pattern file Search for pattern in file
- grep -r pattern dir Search recursively for pattern in dir
- command | grep pattern Search pattern in the output of a command
- locate file Find all instances of file
- find . -name filename Searches in the current directory (represented by a period) and below it, for files and directories with names starting with filename
- pgrep pattern Searches for all the named processes , that matches with the pattern and, by default, returns their ID
[root@cisco ~]# cat /etc/*release
CentOS release 6.2 (Final)
[root@cisco ~]# lsb_release -a
LSB Version: :core-4.0-ia32:core-4.0-noarch:graphics-4.0-ia32:graphics-4.0-noarch:printing-4.0-ia32:printing-4.0-noarch
Distributor ID: CentOS
Description: CentOS release 6.2 (Final)
Release: 6.2
Codename: Final
ps uw -p <pid>
[root@VPC50 ~]# ps -ef | grep netconfd
root 1369 1224 0 16:26 pts/0 00:00:00 netconfd --superuser=root
root 1577 1516 0 16:31 pts/2 00:00:00 grep --color=auto netconfd
[root@VPC50 ~]# ps uw -p 1369
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1369 0.0 0.6 18748 6064 pts/0 S+ 16:26 0:00 netconfd --superuser=root
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