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Basic Commands
This page will list the most basic Linux commands that you would use most commonly and the list will get longer as times goes. There are a group of commands that are pretty often used but not in this page, e.g, Network/IP related command or System Management commands. These commands are not listed here because they will be posted as a separate page.
List of the command in the order of usage
Followings are the list of Linux commands with respect to how often it is used. This is based on my own usage, you would have different order depending on your usage. (You can get the list in Alphabetical Order in following section).
NOTE : You may refer to following sites for quick reference of various linux commands
List of the command in Alphabetical Order
: List the files in a directory
Example : print out the files and directories within the current working directory
$ ls
bin dev initrd.img lib64 mnt root selinux tmp vmlinuz boot etc initrd.img.old lost+found opt run srv usr vmlinuz.old cdrom home lib media proc sbin sys var
Example : print out all the files and directory within the current working directory with property informal
$ ls -al
drwxr-xr-x 24 root root 4096 May 30 02:48 . drwxr-xr-x 24 root root 4096 May 30 02:48 .. drwxr-xr-x 2 root root 4096 May 30 23:45 bin
'''''' drwxr-xr-x 10 root root 4096 Feb 13 17:07 usr drwxr-xr-x 13 root root 4096 May 30 09:18 var lrwxrwxrwx 1 root root 29 May 30 02:48 vmlinuz -> boot/vmlinuz-3.5.0-31-generic lrwxrwxrwx 1 root root 29 May 30 09:57 vmlinuz.old -> boot/vmlinuz-3.5.0-23-generic
Example : print out the list in all the sub directories ('R' stands for Recursive)
$ ls -R
Example : print out all the list in page by page. When it goes over a page, the list stops at the end of a page with '-- More --'. It shows you one more line as you press Enter key.
drwxr-xr-x 24 root root 4096 May 30 02:48 . drwxr-xr-x 24 root root 4096 May 30 02:48 .. drwxr-xr-x 2 root root 4096 May 30 23:45 bin
'''''' drwxr-xr-x 10 root root 4096 Feb 13 17:07 usr drwxr-xr-x 13 root root 4096 May 30 09:18 var lrwxrwxrwx 1 root root 29 May 30 02:48 vmlinuz -> boot/vmlinuz-3.5.0-31-generic lrwxrwxrwx 1 root root 29 May 30 09:57 vmlinuz.old -> boot/vmlinuz-3.5.0-23-generic -- More -- <-- It shows next line as you press [Enter]. Press 'Q' to quit
Example : List the files and directories in a specified folder
$ ls /var
backups cache crash games lib local lock log mail opt run spool tmp
Example : print out all the list which contains the specified string. Following example lists all the file name and directory names which contains the string 'edit' in it.
$ ls -al usr/bin | grep 'edit'
lrwxrwxrwx 1 root root 20 Jan 19 15:43 desktop-file-edit -> desktop-file-install lrwxrwxrwx 1 root root 11 Jan 19 15:43 edit -> run-mailcap -rwxr-xr-x 1 root root 2060 May 6 2015 editdiff ... -rwxr-xr-x 1 root root 645880 Feb 10 2016 xedit
: find files
Example : list all the files in current directory and sub directories
$ find
Example : list all the files in current directory and sub directories
$ find .
Example : list all the files with a specified pattern within the current directory and sub directories. This example list all the filenames starting with 'Hello'.
$ find . -name 'Hello*' or $ find -name 'Hello*'
Example : list all the files with a specified pattern in the whole PC. This example list all the filenames starting with 'Hello'.
$ sudo find / -name 'Hello*' or $ sudo find / | grep 'Hello'
NOTE : I put 'sudo' here because there can be many folders which has a limitted permission. If you don't put sudo, this would not search the folder with limited permission.
: Shows the path for the current directory
Example
#pwd
/home/sharetechnote
: Provide the super user previlege
Example :
$
ifconfig eth0 192.168.1.2 up
SIOCSIFADDR: Permission denied <-- this Linux does not allow to change ifconfig SIOCSIFFLAGS: Permission denied
$ sudo ifconfig eth0 192.168.1.2 up <-- try the same command with super user previlege
[sudo] password for sharetechnote: <-- type in the password and then it will allow the command to be executed
: delete a file or directory
Example :
# rm usbstick
Example : you may get an error message when you remove a directory with rm as shown below. In that case, you may use '-r' or '-rf' option to remove the whole directory.
# rm usbstick
rm: cannot remove `usbstick': Is a directory <-- rm failed to remove usbstick
# rm -r usbstick <-- try with '-r' option
# rm -rf usbstick <-- try with '-rf' option
: View the contents of a file
Example :
$ cat temp.txt
Contents of 'temp.txt' will show up here ....
Example :
$ cat file1 file2
Contents of file1 and file2 will show up in sequence ....
Example :
$ cat file1 file2 > file3
Contents of file1 and file2 will be out to file3. In other words, file1 and file2 concatenated and create file3. ....
: map an hardware to a specific directory.
Example 1 : map a usb stick to a directory (This is done on Ubuntu)
Step 1: Create a directory to be mapped to a IO device (you can use an existing directory as well)
# mkdir /mnt/usbstick
Step 2: Make it sure that the directory is created properly.
# ls /mnt
usbstick
Step 3: Make it sure that the directory is created properly.
# mount -t vfat -o rw,users /dev/sda2 /mnt/usbstick <-- with vfat, you can mount usbstick which is formated on Windows <-- /dev/sda2 is the usb port that my usb stick is plugged in. you have to make it sure that you have specified the right port number. you may try 'fdisk -l' command to figure out which device you have to use for this mount
Step 4: check if it is properly mounted. The simplest way would be to use 'ls' and see if it shows the contents that is stored in the stick.
# ls /mnt/usbstick
temp.txt
: Display the list of processes currently running on a machine. It is same as "Processe" tab on Task Manager in Windows.
Example :
# ps
PID TTY TIME CMD 2079 pts/1 00:00:00 su 2087 pts/1 00:00:00 bash 16819 pts/1 00:00:00 ps
Example :
# ps -al <-- Note 'a' is in lower case
F S UID PID PPID C PRI NI ADDR SZ WCHAN TTY TIME CMD 4 S 0 2079 2021 0 80 0 - 15478 wait pts/1 00:00:00 su 0 S 0 2087 2079 0 80 0 - 6810 wait pts/1 00:00:00 bash 0 R 0 16822 2087 0 80 0 - 3482 - pts/1 00:00:00 ps
Example :
# ps -Al <-- Note 'a' is in upper case
F S UID PID PPID C PRI NI ADDR SZ WCHAN TTY TIME CMD 4 S 0 1 0 0 80 0 - 6117 poll_s ? 00:00:01 init 1 S 0 2 0 0 80 0 - 0 kthrea ? 00:00:00 kthreadd 1 S 0 3 2 0 80 0 - 0 run_ks ? 00:00:07 ksoftirqd/0 1 S 0 6 2 0 -40 - - 0 cpu_st ? 00:00:01 migration/0 1 S 0 7 2 0 -40 - - 0 watchd ? 00:00:00 watchdog/0 1 S 0 20 2 0 60 -20 - 0 rescue ? 00:00:00 cpuset 1 S 0 21 2 0 60 -20 - 0 rescue ? 00:00:00 khelper 5 S 0 22 2 0 80 0 - 0 devtmp ? 00:00:00 kdevtmpfs ... 4 S 0 837 1 0 80 0 - 19760 poll_s ? 00:00:00 modem-manager 5 S 0 838 1 0 80 0 - 5297 poll_s ? 00:00:00 bluetoothd 5 S 0 849 2 0 70 -10 - 0 rfcomm ? 00:00:00 krfcommd 5 S 0 851 1 0 80 0 - 61343 poll_s ? 00:00:24 NetworkManager ..... 0 S 1000 1729 1721 0 80 0 - 2845 unix_s ? 00:00:00 cat .... 0 S 1000 2021 2009 0 80 0 - 6799 wait pts/1 00:00:00 bash 4 S 0 2079 2021 0 80 0 - 15478 wait pts/1 00:00:00 su 0 S 0 2087 2079 0 80 0 - 6810 wait pts/1 00:00:00 bash .... 0 S 1000 14645 1 3 80 0 - 264797 poll_s ? 00:22:43 firefox
Example :
# ps -aux
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 1 0.3 0.2 119696 5756 ? Ss 17:12 0:01 /sbin/init spla root 2 0.0 0.0 0 0 ? S 17:12 0:00 [kthreadd] root 3 0.0 0.0 0 0 ? S 17:12 0:00 [kworker/0:0] root 4 0.0 0.0 0 0 ? S< 17:12 0:00 [kworker/0:0H] root 6 0.0 0.0 0 0 ? S< 17:12 0:00 [mm_percpu_wq] root 7 0.0 0.0 0 0 ? S 17:12 0:00 [ksoftirqd/0] root 8 0.0 0.0 0 0 ? S 17:12 0:00 [rcu_sched] root 9 0.0 0.0 0 0 ? S 17:12 0:00 [rcu_bh] ... root 80 0.0 0.0 0 0 ? S 17:12 0:00 [scsi_eh_1] root 81 0.0 0.0 0 0 ? S< 17:12 0:00 [scsi_tmf_1] root 82 0.0 0.0 0 0 ? S 17:12 0:00 [kworker/u2:2] root 87 0.0 0.0 0 0 ? S< 17:12 0:00 [ipv6_addrconf] root 112 0.0 0.0 0 0 ? S< 17:12 0:00 [charger_manage root 113 0.0 0.0 0 0 ? S 17:12 0:00 [kworker/u2:4] root 155 0.0 0.0 0 0 ? S< 17:12 0:00 [kworker/0:1H] .. root 704 0.0 0.1 29008 3008 ? Ss 17:12 0:00 /usr/sbin/cron root 710 0.0 0.4 291404 8184 ? Ssl 17:12 0:00 /usr/lib/accoun root 735 0.0 1.0 136076 20488 ? Ssl 17:12 0:00 /usr/lib/snapd/ syslog 744 0.0 0.1 256396 3368 ? Ssl 17:12 0:00 /usr/sbin/rsysl avahi 749 0.0 0.1 44908 3504 ? Ss 17:12 0:00 avahi-daemon: r root 750 0.0 0.8 455848 17076 ? Ssl 17:12 0:00 /usr/sbin/Netwo avahi 758 0.0 0.0 44784 336 ? S 17:12 0:00 avahi-daemon: c root 763 0.0 0.0 4396 1316 ? Ss 17:12 0:00 /usr/sbin/acpid root 812 0.0 0.2 65508 5640 ? Ss 17:12 0:00 /usr/sbin/sshd ... root 865 0.0 0.1 16128 3728 ? S 17:12 0:00 /sbin/dhclient root 866 0.0 0.1 16128 3724 ? S 17:12 0:00 /sbin/dhclient nobody 888 0.0 0.1 52864 3960 ? S 17:12 0:00 /usr/sbin/dnsma root 953 0.0 0.3 228240 6364 ? Sl 17:12 0:00 lightdm --sessi jaekuryu 976 0.0 0.2 45248 4652 ? Ss 17:12 0:00 /lib/systemd/sy jaekuryu 978 0.0 0.0 63312 1936 ? S 17:12 0:00 (sd-pam) ... jaekuryu 1486 0.0 0.1 42896 3928 ? S 17:12 0:00 /usr/bin/dbus-d ... root 2562 0.0 0.0 0 0 ? S 17:18 0:00 [kworker/u2:0] jaekuryu 2564 0.0 0.1 37364 3312 pts/17 R+ 17:18 0:00 ps -aux
: kill a specific process
Example :
#kill 14645 <-- 14645 in this example is the PID for the process you want to kill. You have to figure out the PID using ps command
: change access property of a file or directory
Example :
#chmod 777 myfile <-- set the access property of the file named 'myfile' to be 'readable, writeable, executable' to all users, all groups.
Example :
#chmod 666 myfile <-- set the access property of the file named 'myfile' to be 'readable, writeable, Not executable' to all users, all groups.
Example :
#chmod 555 myfile <-- set the access property of the file named 'myfile' to be 'readable, Not writeable, executable' to all users, all groups.
: find a specified string from a file or the output of other command
Example :
#grep hello mytext <-- search the string 'hello' from the file named 'mytext' and displays the lines containing the string 'hello'.
Example :
#ls -Al | grep hello <-- execute 'ls -Al' and find the string 'hello' from the output of 'ls -Al' and displays the line containing th string 'hello'. This may be the most common example of 'grep' command.
: Indicate 'current directory'. When we execute a specific program, we normally type in the 'filename' and press enter. If the executable file is located in a directory specified '$PATH', it executes.. but if it is not in one of these PATH, the system would shows error saying 'No command 'xxxxx' found'. In this case, you have to specify the explicit path(location) of the executable before the filename to run it. If you are currently at the directory where the executable, you can just put "./" before the filename.
Example :
#./myprogram <-- run the executable named 'myprogram' located in 'current directory'. If 'myprogram' is not in the current directory, the system would show 'No command 'xxxxx' found'.
This command lists information on all the storage device that are currently connected to the PC. it will be helpful to figure out device name to mount for external storage device (e.g, usb memory stick etc)
Example 1 >
# fdisk -l <-- this would run when you logged in as root, but it may not work if you are not in root account
Example 2 >
# sudo fdisk -l <-- you may try this if you are not logged in as root
This command list the status of all the modules (device drivers) in the Linux Kernel
Example 1 >
# lsmod
Module Size Used by tcp_lp 12663 0 ip6table_filter 12815 0 ip6_tables 26808 1 ip6table_filter ebtable_nat 12807 0 ebtables 30758 1 ebtable_nat sctp 317063 18 libcrc32c 12603 1 sctp tun 27153 2 ipt_MASQUERADE 12880 4 iptable_nat 13011 1 nf_conntrack_ipv4 14656 1 nf_defrag_ipv4 12702 1 nf_conntrack_ipv4 nf_nat_ipv4 13199 1 iptable_nat nf_nat 25112 3 ipt_MASQUERADE,nf_nat_ipv4,iptable_nat nf_conntrack 95080 5 ipt_MASQUERADE,nf_nat,nf_nat_ipv4,iptable_nat,nf_conntrack_ipv4 joydev 17332 0 btusb 28290 0 bluetooth 408436 2 btusb hid_logitech_dj 18581 0 6lowpan_iphc 18591 1 bluetooth mxm_wmi 12865 0 coretemp 13475 0 kvm_intel 143109 0 kvm 460312 1 kvm_intel ....
This is a command-line tool for working with APT(Advanced Packaging Tool) software packages. I think this is one of the most covinient command to install a new software on various linux family (e.g, Ubuntu). Basic syntax is as shown below. Refer to Linux and Unix apt-get command for the detailed tutorial.
apt-get [-asqdyfmubV] [-o=config_string] [-c=config_file] [-t=target_release] [-a=architecture] {update | upgrade | dselect-upgrade | dist-upgrade | install pkg [{=pkg_version_number | /target_release}]... | remove pkg... | purge pkg... | source pkg [{=pkg_version_number | /target_release}]... | build-dep pkg [{=pkg_version_number | /target_release}]... | download pkg [{=pkg_version_number | /target_release}]... | check | clean | autoclean | autoremove | {-v | --version} | {-h | --help}}
Since most of programming installation requires super user authority, so in most case you would use like 'sudo apt-get xxxxxx'.
Example >
I don't put any specific example here. The best way to use the command is to try Google 'How to install xxxx program (e.g, Chrome) in linux (e.g, Ubuntu) ?' and copy the whole command from the searched page and run it in your linux.
: When you are running a certain program, there are cases where you get errors saying 'a xxxx file is missing'. In this case, you need to install a package that containing the missing file. Now the question is 'how can I figure out the package name that contains the missing file ?'. apt-file is the tool you need to use to find the info.
Note : the tool apt-file might have not been installed on your PC by defailt. In that case, you need to install the tool first by following command.
# sudo apt install apt-file
If you just installed the apt-file, you need to do following to download all the package info into your PC. Otherwise, apt-file would not be able to search the information that you need.
# apt-file update
Example > : I will show you a sample case in which how and when you need to use this command
# ./qt-linux-opensource-5.0.2-x86-offline.run // I executed a program as shown here (you would run some other program as you need. this is just my example) // and I got following error
./qt-linux-opensource-5.0.2-x86-offline.run: error while loading shared libraries: libXrender.so.1: cannot open shared object file: No such file or directory // it says libXrender.so.1 is missing. So I want to find out which package has this file using following command
# apt-file search libXrender.so.1 // I got following result
libxrender1: /usr/lib/x86_64-linux-gnu/libXrender.so.1 libxrender1: /usr/lib/x86_64-linux-gnu/libXrender.so.1.3.0 libxrender1-dbg: /usr/lib/debug/usr/lib/x86_64-linux-gnu/libXrender.so.1.3.0
Then I install the package as follows
# sudo apt-get install libxrender1:i386
YUM (Yellowdog Updater Modified) is an open source command-line as well as graphical based package management tool for RPM (RedHat Package Manager) based Linux systems.
Basic syntax of yum command is as follows. (put yum in the place of *). Refer to yum-LinuxCommand.org for detailed usage. * install package1 [package2] [...] * update [package1] [package2] [...] * check-update * upgrade [package1] [package2] [...] * remove | erase package1 [package2] [...] * list [...] * info [...] * provides | whatprovides feature1 [feature2] [...] * clean [ packages | headers | metadata | cache | dbcache | all ] * makecache * groupinstall group1 [group2] [...] * groupupdate group1 [group2] [...] * grouplist [hidden] * groupremove group1 [group2] [...] * groupinfo group1 [...] * search string1 [string2] [...] * shell [filename] * resolvedep dep1 [dep2] [...] * localinstall rpmfile1 [rpmfile2] [...] * localupdate rpmfile1 [rpmfile2] [...] * deplist package1 [package2] [...]
Example >
I don't put any specific example here. The best way to use the command is to try Google 'How to install xxxx program (e.g, Chrome) in linux (e.g, Fedora) ?' and copy the whole command from the searched page and run it in your linux.
This command list (shows) the CPU information of the PC on which you are running the Linux.
Example :
# lscpu
Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Byte Order: Little Endian CPU(s): 4 On-line CPU(s) list: 0-3 Thread(s) per core: 2 Core(s) per socket: 2 Socket(s): 1 NUMA node(s): 1 Vendor ID: GenuineIntel CPU family: 6 Model: 42 Stepping: 7 CPU MHz: 800.000 BogoMIPS: 2993.22 Virtualization: VT-x L1d cache: 32K L1i cache: 32K L2 cache: 256K L3 cache: 3072K NUMA node0 CPU(s): 0-3
This command prints all block devices (except RAM disks) in a tree format (by default)
Example :
#lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 465.8G 0 disk +-sda1 8:1 0 149G 0 part +-sda2 8:2 0 161G 0 part +-sda3 8:3 0 1K 0 part +-sda5 8:5 0 151.8G 0 part / +-sda6 8:6 0 3.9G 0 part [SWAP] sr0 11:0 1 3.5G 0 rom /media/ResourceCD
This command convert an executable binary file to assembly code. The format of the command is as follows : objdump <options> <file>
Example :
# objdump -D -Mintel,x86-64 -b binary -m i386 -Maddr32,data32 sda-mbr.bin <-- convert sda-mbr.bin file into assembly code (display sda-mbr.bin in assembly code format) with using the options : -D -Mintel,x86-64 -b binary -m i386 -Maddr32,data32
sda-mbr.bin: file format binary
Disassembly of section .data:
00000000 <.data>: 0: eb 63 jmp 0x65 2: 90 nop ... 3b: 00 00 add BYTE PTR [eax],al 3d: 00 03 add BYTE PTR [ebx],al 3f: 02 ff add bh,bh 41: 00 00 add BYTE PTR [eax],al 43: 20 01 and BYTE PTR [ecx],al 45: 00 00 add BYTE PTR [eax],al ....
This command finds path+filename of a specified file (mostly an executable program). This command searches the files through the locations specifed in PATH parameter of the operating system
Example :
# which gcc <-- find the path where gcc is located
/usr/bin/gcc
You can shutdown or reboot the linux using various options of this command. Try "shutdown --help" to find the details.
Example :
#sudo shutdown -h now <-- shutdown (power off) the PC
Example :
#sudo shutdown -r now <-- reboot the PC
: print out the enviroment variables
Example :
#env
XDG_VTNR=7 XDG_SESSION_ID=c1 CLUTTER_IM_MODULE=xim XDG_GREETER_DATA_DIR=/var/lib/lightdm-data/sharetechnote SESSION=ubuntu GPG_AGENT_INFO=/home/jaekuryu/.gnupg/S.gpg-agent:0:1 SHELL=/bin/bash TERM=xterm-256color VTE_VERSION=4205 QT_LINUX_ACCESSIBILITY_ALWAYS_ON=1 WINDOWID=56623114 UPSTART_SESSION=unix:abstract=/com/ubuntu/upstart-session/1000/1030 GNOME_KEYRING_CONTROL= GTK_MODULES=gail:atk-bridge:unity-gtk-module USER=sharetechnote LS_COLORS=rs=0:di=01;34:ln=01;36:mh=00:...;36: QT_ACCESSIBILITY=1 XDG_SESSION_PATH=/org/freedesktop/DisplayManager/Session0 XDG_SEAT_PATH=/org/freedesktop/DisplayManager/Seat0 SSH_AUTH_SOCK=/run/user/1000/keyring/ssh DEFAULTS_PATH=/usr/share/gconf/ubuntu.default.path XDG_CONFIG_DIRS=/etc/xdg/xdg-ubuntu:/usr/share/upstart/xdg:/etc/xdg PATH=/home/sharetechnoe/bin:...:/usr/local/games:/snap/bin DESKTOP_SESSION=ubuntu QT_IM_MODULE=ibus QT_QPA_PLATFORMTHEME=appmenu-qt5 XDG_SESSION_TYPE=x11 PWD=/home/sharetechnote JOB=unity-settings-daemon XMODIFIERS=@im=ibus GNOME_KEYRING_PID= LANG=en_CA.UTF-8 GDM_LANG=en_CA MANDATORY_PATH=/usr/share/gconf/ubuntu.mandatory.path IM_CONFIG_PHASE=1 COMPIZ_CONFIG_PROFILE=ubuntu-lowgfx GDMSESSION=ubuntu SESSIONTYPE=gnome-session GTK2_MODULES=overlay-scrollbar HOME=/home/sharetechnote XDG_SEAT=seat0 SHLVL=1 LANGUAGE=en_CA:en LIBGL_ALWAYS_SOFTWARE=1 GNOME_DESKTOP_SESSION_ID=this-is-deprecated UPSTART_INSTANCE= UPSTART_EVENTS=xsession started XDG_SESSION_DESKTOP=ubuntu LOGNAME=jaekuryu COMPIZ_BIN_PATH=/usr/bin/ QT4_IM_MODULE=xim XDG_DATA_DIRS=/usr/share/ubuntu:...:/var/lib/snapd/desktop DBUS_SESSION_BUS_ADDRESS=unix:abstract=/tmp/dbus-e6LwXeFYYa LESSOPEN=| /usr/bin/lesspipe %s INSTANCE= UPSTART_JOB=unity7 XDG_RUNTIME_DIR=/run/user/1000 DISPLAY=:0 XDG_CURRENT_DESKTOP=Unity GTK_IM_MODULE=ibus LESSCLOSE=/usr/bin/lesspipe %s %s XAUTHORITY=/home/sharetechnote/.Xauthority OLDPWD=/home _=/usr/bin/env
: print out the enviroment variables
Example :
#printenv
XDG_VTNR=7 XDG_SESSION_ID=c1 CLUTTER_IM_MODULE=xim XDG_GREETER_DATA_DIR=/var/lib/lightdm-data/sharetechnote SESSION=ubuntu GPG_AGENT_INFO=/home/jaekuryu/.gnupg/S.gpg-agent:0:1 SHELL=/bin/bash TERM=xterm-256color VTE_VERSION=4205 QT_LINUX_ACCESSIBILITY_ALWAYS_ON=1 WINDOWID=56623114 UPSTART_SESSION=unix:abstract=/com/ubuntu/upstart-session/1000/1030 GNOME_KEYRING_CONTROL= GTK_MODULES=gail:atk-bridge:unity-gtk-module USER=sharetechnote LS_COLORS=rs=0:di=01;34:ln=01;36:mh=00:...;36: QT_ACCESSIBILITY=1 XDG_SESSION_PATH=/org/freedesktop/DisplayManager/Session0 XDG_SEAT_PATH=/org/freedesktop/DisplayManager/Seat0 SSH_AUTH_SOCK=/run/user/1000/keyring/ssh DEFAULTS_PATH=/usr/share/gconf/ubuntu.default.path XDG_CONFIG_DIRS=/etc/xdg/xdg-ubuntu:/usr/share/upstart/xdg:/etc/xdg PATH=/home/sharetechnoe/bin:...:/usr/local/games:/snap/bin DESKTOP_SESSION=ubuntu QT_IM_MODULE=ibus QT_QPA_PLATFORMTHEME=appmenu-qt5 XDG_SESSION_TYPE=x11 PWD=/home/sharetechnote JOB=unity-settings-daemon XMODIFIERS=@im=ibus GNOME_KEYRING_PID= LANG=en_CA.UTF-8 GDM_LANG=en_CA MANDATORY_PATH=/usr/share/gconf/ubuntu.mandatory.path IM_CONFIG_PHASE=1 COMPIZ_CONFIG_PROFILE=ubuntu-lowgfx GDMSESSION=ubuntu SESSIONTYPE=gnome-session GTK2_MODULES=overlay-scrollbar HOME=/home/sharetechnote XDG_SEAT=seat0 SHLVL=1 LANGUAGE=en_CA:en LIBGL_ALWAYS_SOFTWARE=1 GNOME_DESKTOP_SESSION_ID=this-is-deprecated UPSTART_INSTANCE= UPSTART_EVENTS=xsession started XDG_SESSION_DESKTOP=ubuntu LOGNAME=jaekuryu COMPIZ_BIN_PATH=/usr/bin/ QT4_IM_MODULE=xim XDG_DATA_DIRS=/usr/share/ubuntu:...:/var/lib/snapd/desktop DBUS_SESSION_BUS_ADDRESS=unix:abstract=/tmp/dbus-e6LwXeFYYa LESSOPEN=| /usr/bin/lesspipe %s INSTANCE= UPSTART_JOB=unity7 XDG_RUNTIME_DIR=/run/user/1000 DISPLAY=:0 XDG_CURRENT_DESKTOP=Unity GTK_IM_MODULE=ibus LESSCLOSE=/usr/bin/lesspipe %s %s XAUTHORITY=/home/sharetechnote/.Xauthority OLDPWD=/home _=/usr/bin/env
: Create an empty file or multiple files. And you can change some file attributes (e.g, timestamp) with this command.
Example :
#touch temp.txt <-- this will create an empty file named temp.txt
#ls -al
drwxrwxr-x 2 sharetechnote sharetechnote 4096 Jan 26 16:51 . drwxr-xr-x 21 sharetechnote sharetechnote 4096 Jan 26 16:51 .. -rw-rw-r-- 1 sharetechnote sharetechnote 0 Jan 26 16:51 temp.txt <-- See size of the file is 0.
Example :
#touch temp1.txt temp2.txt temp3.txt <-- this will create three empty files named temp1.txt , temp2.txt and temp3.txt
#ls -al
-rw-rw-r-- 1 sharetechnote sharetechnote 0 Jan 26 17:06 temp1.txt -rw-rw-r-- 1 sharetechnote sharetechnote 0 Jan 26 17:06 temp2.txt -rw-rw-r-- 1 sharetechnote sharetechnote 0 Jan 26 17:06 temp3.txt -rw-rw-r-- 1 sharetechnote sharetechnote 0 Jan 26 16:51 temp.txt
Example :
#touch -m temp1.txt <-- this will update the time stamp for temp1.txt with the current time.
#ls -al
-rw-rw-r-- 1 sharetechnote sharetechnote 0 Jan 26 17:09 temp1.txt -rw-rw-r-- 1 sharetechnote sharetechnote 0 Jan 26 17:06 temp2.txt -rw-rw-r-- 1 sharetechnote sharetechnote 0 Jan 26 17:06 temp3.txt -rw-rw-r-- 1 sharetechnote sharetechnote 0 Jan 26 16:51 temp.txt
: monitor processes and system resource usage (This is similar to the TaskManager in Windows)
Example :
#top
Tasks: 151 total, 1 running, 150 sleeping, 0 stopped, 0 zombie %Cpu(s): 2.4 us, 0.3 sy, 0.0 ni, 97.0 id, 0.3 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem : 2041572 total, 453092 free, 743648 used, 844832 buff/cache KiB Swap: 2095100 total, 2095100 free, 0 used. 1110616 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 859 root 20 0 499476 117240 36352 S 1.0 5.7 0:27.74 Xorg 1752 jaekuryu 20 0 1262740 206332 76312 S 1.0 10.1 3:53.14 compiz 2020 jaekuryu 20 0 662668 35800 28244 S 1.0 1.8 0:02.24 gnome-termi+ 1409 jaekuryu 20 0 358292 8452 7092 S 0.3 0.4 0:00.51 ibus-daemon 1492 jaekuryu 20 0 206972 5316 4828 S 0.3 0.3 0:00.11 at-spi2-reg+ 1680 jaekuryu 20 0 567212 33008 25572 S 0.3 1.6 0:00.59 unity-panel+ 1737 jaekuryu 20 0 659580 26916 21684 S 0.3 1.3 0:00.12 indicator-k+ 2796 root 20 0 0 0 0 S 0.3 0.0 0:00.28 kworker/0:0 2809 jaekuryu 20 0 41800 3576 3020 R 0.3 0.2 0:00.08 top 1 root 20 0 119696 5756 3908 S 0.0 0.3 0:01.23 systemd 2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd 4 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kworker/0:0H 6 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 mm_percpu_wq 7 root 20 0 0 0 0 S 0.0 0.0 0:00.18 ksoftirqd/0 8 root 20 0 0 0 0 S 0.0 0.0 0:00.17 rcu_sched 9 root 20 0 0 0 0 S 0.0 0.0 0:00.00 rcu_bh 10 root rt 0 0 0 0 S 0.0 0.0 0:00.00 migration/0 jaekuryu 1926 0.0 0.2 271724 4908 ? Sl 17:13 0:00 /usr/lib/gvfs/g jaekuryu 1933 0.0 0.4 403644 8864 ? Sl 17:13 0:00 /usr/lib/gvfs/g jaekuryu 1943 0.0 0.2 257564 5092 ? Sl 17:13 0:00 /usr/lib/gvfs/g jaekuryu 1952 0.0 0.2 259528 4452 ? Sl 17:13 0:00 /usr/lib/gvfs/g jaekuryu 1982 0.0 0.4 363700 8388 ? Sl 17:13 0:00 /usr/lib/gvfs/g jaekuryu 2020 0.2 1.7 662284 35296 ? Sl 17:13 0:00 /usr/lib/gnome- jaekuryu 2026 0.0 0.2 22424 4864 pts/17 Ss 17:13 0:00 bash jaekuryu 2041 0.0 0.8 498104 16372 ? Sl 17:13 0:00 zeitgeist-datah jaekuryu 2048 0.0 0.0 4504 780 ? S 17:13 0:00 /bin/sh -c /usr jaekuryu 2055 0.0 0.3 405504 6420 ? Sl 17:13 0:00 /usr/bin/zeitge jaekuryu 2063 0.0 0.4 310840 9776 ? Sl 17:13 0:00 /usr/lib/x86_64 jaekuryu 2109 0.0 1.2 600028 25740 ? Sl 17:14 0:00 update-notifier jaekuryu 2131 2.6 6.6 710956 136168 ? SNl 17:14 0:07 /usr/bin/python root 2163 0.6 5.1 289900 104272 ? SNl 17:14 0:01 /usr/bin/python jaekuryu 2518 0.0 0.4 588856 8808 ? Sl 17:15 0:00 /usr/lib/x86_64 jaekuryu 2541 0.1 1.5 571996 31096 ? Sl 17:17 0:00 deja-dup --prom root 2562 0.0 0.0 0 0 ? S 17:18 0:00 [kworker/u2:0] jaekuryu 2564 0.0 0.1 37364 3312 pts/17 R+ 17:18 0:00 ps -aux
: dd stands for 'data duplicator'. This is mained used for copying a file (mainly a portion of disk) to a file or converting the data format of a file (or a portion of disk) into another format. dd if=<source file name> of=<target file name> [Options]
NOTE : if stands for 'input file' and of stands for output file. dd is a very powerful / flexible tool and can be used with a lot of different options which would take time to get familiar with. For general concept and simple examples, refer to this, this and this page which would be much better than my explanation. You may also see my example that I used when I am analyzing MBR (Master Boot Record) here.
: dd stands for 'data duplicator'. This is mained used for copying a file (mainly a portion of disk) to a file or converting the data format of a file (or a portion of disk) into another format. dd if=<source file name> of=<target file name> [Options]
NOTE : if stands for 'input file' and of stands for output file. dd is a very powerful / flexible tool and can be used with a lot of different options which would take time to get familiar with. For general concept and simple examples, refer to this, this and this page which would be much better than my explanation. You may also see my example that I used when I am analyzing MBR (Master Boot Record) here.
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