Linux commands and utilities

This is a list of common CentOS Linux commands and utilities a Bahmni implementer should know for daily system administration. There is plenty of materials online that would help you to master these commands and its various options. This list will only tell you what commands you should start looking up.

Command	Description	Example	Read More
ls	List files in current directory	ls -al	http://www.tecmint.com/15-basic-ls-command-examples-in-linux/
touch	Creates an empty file
cat	Shows the contents of a file	cat hello.txt
man	Show help for a command	man cat
chmod	Change the file access permissions to give read/write/execute permissions to a file or files	chmod +x myscript.sh	https://en.wikipedia.org/wiki/Chmod
chown	Change the file owner / group owner	chown bahmni:bahmni -R /var/www/	http://www.linfo.org/chown.html
chgrp	Change the group ownership
grep	Finds matching data in text inputs using regular expressions	cat hello.txt \| grep "bahmni"	http://www.thegeekstuff.com/2009/03/15-practical-unix-grep-command-examples/
pwd	Shows the current directory path (pwd = present working directory)
cd	Change into the specified directory	cd /home
tail	Display the last few contents of a text file. Useful for seeing log files.	tail -f /var/log/openmrs/openmrs.log	http://www.thegeekstuff.com/2009/08/10-awesome-examples-for-viewing-huge-log-files-in-unix/
cp	Copies a file from one location to another	cp abc.txt /home
mv	Moves a file to another location. Also used for renaming a file.	mb abc1.txt abc2.txt
rm	Delete a file or a directory	rm /tmp/hello
mkdir	Create a new directory	mkdir music
find	Used for searching files matching a certain pattern. Can also be used to execute specific commands on files which match a certain pattern	find -name "*.mp3"	http://www.tecmint.com/35-practical-examples-of-linux-find-command/
ps -ef	Print all currently running processes.	ps -ef \| grep java	https://www.digitalocean.com/community/tutorials/how-to-use-ps-kill-and-nice-to-manage-processes-in-linux
df	Print disk space usage (short for 'disk free')
du	Print disk usage report for current directory	du -sh	http://www.tecmint.com/check-linux-disk-usage-of-files-and-directories/
clear	Clear the screen
tar	For creating or extracting tar files -xvf <filename.tar> extract tar file -cvf <filename.tar> compress files and folders -tvf archive.tar List all files in archive.tar verbosely.		http://www.tecmint.com/18-tar-command-examples-in-linux/
yum	Manage installations of RPMs / softwares.	yum install bahmni-emr yum remove bahmni-emr yum info bahmni-emr	https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Deployment_Guide/ch-yum.html
kill	Terminate a process / Raise a Signal	kill -9 <pid>	https://www.maketecheasier.com/kill-command-in-linux/
ifconfig	Print network configuration / IP of the machine
scp	Secure copy of files (over SSH port)	scp -r foo john@remotehost:/tmp	http://www.hypexr.org/linux_scp_help.php
chkconfig	Updates and queries runlevel information for system services		https://blog.sleeplessbeastie.eu/2012/07/07/centos-how-to-manage-system-services/
service	Provide information on registered system services.	service bahmni-emr status service bahmni-emr stop service bahmni-emr start	https://blog.sleeplessbeastie.eu/2012/07/07/centos-how-to-manage-system-services/
whoami	Prints the details of the current user
useradd	Add user to system		http://www.liquidweb.com/kb/how-to-add-a-user-and-grant-root-privileges-on-centos-6-5/
passwd	Set password of the user
sudo	Run with root privilege	sudo service bahmni-emr stop	https://www.garron.me/en/linux/visudo-command-sudoers-file-sudo-default-editor.html
ssh	SSH to a remote machine	ssh root@192.133.8.10	http://support.suso.com/supki/SSH_Tutorial_for_Linux
ping	Check if a Ping message can be sent over a network	ping www.google.com
crontab	Configure cron job (for scheduled tasks)	crontab -L	https://www.pantz.org/software/cron/croninfo.html
mount	Mount a disk (partition) on a particular path
umount	Un-mount a disk
vi	Editor for files	vi hello.txt	http://www.howtogeek.com/102468/a-beginners-guide-to-editing-text-files-with-vi/ http://www.openvim.com/ (Online VIM tutorial)
iptables	Firewall on Linux		https://wiki.centos.org/HowTos/Network/IPTables
history	List last / all executed commands		http://www.tecmint.com/history-command-examples/
top	show processor and memory as being used and other information like running processes	top	http://www.tecmint.com/12-top-command-examples-in-linux/ Further reading : htop : http://www.tecmint.com/install-htop-linux-process-monitoring-for-rhel-centos-fedora/
free	gives understanding of total available space of physical memory and swap memory	free -m	http://www.tecmint.com/check-memory-usage-in-linux/