command_bk

### YUM (Yellowdog Updater and Modifier)

	~$yum install <pkg>
	~$yum upgrade <pkg>
	~$yum localinsatll <pkg*>
	~$yum remove <pkg/command/rpm>
	~$yum history list #install/update/upgrade or transaction history
	~$yum history list all 
	~$yum history info <id> #pkg info install/update/upgrade or transaction history by id
	~$yum history undo <id> #undo the transaction by id
	~$yum history redo <id> #redo the transaction by id
	~$yum history new #yum stores transaction in single SQLite db. To start new transaction history
	~$yum whatprovides <pkg/command>
	~$yum --showduplicates list httpd | expand
	~$yum list available java*
	~$yum list installed
	

### Permission 

	~$chmod u+s <file> #set suid bit such as -rwsr-xr-x. small s means (rwxs)
	~$chmod 4655 <file> #set suid bit such as -rwSr-xr-x. capital S means (rws)
	~$Setgid on dir, all dir/files in it will get same ownership as parent dir. It doesn't matter who is creating
	~$chmod g+s <dir/file> #setting setgid bit
	~$chmod 1777 <dir> #setting sticky bit such as drwxrwxrwt. small t means (rwxt)
	~$chmod 1776 <dir> #setting sticky bit such as drwxrwxrwT. capital T means (rwt)
	~$chown -R <user>:<group> <dir> #asssigning recursive permission of all files/dir in  target dir

### User Administration 

	~$useradd <user>
	~$useradd -g itadmin -c "DB User" -u 1135 -s "/bin/sh" -d /home/techguy1 
	In the above command, we are creating the new user with custom options as simple "#useradd <user>" will create with default setting. The -g (group) -c (description) -u (user id) -s (which shell to be assigned) -d (landed home dir)
	~$useradd -g <primary group> -G <secondary group> <user> # assign the user primary and secondary group
	~$passwd -l <user> #locking password of user
	~$passwd -u <user> #unlocking password of user
	~$passwd -e <user> #expire password 
	~$echo 'myPassword123' | sudo passwd --stdin <user> 
	~$passwd -x -1 <user> #Turnoff password expiry
	~$usermod -L <user> #locking user
	~$usermod -U <user> #unlocking user
	~$chage #set password expiry

### Access Control Lists (ACLs)

	~$getfacl <file/dir> #to view the access control list of file/dir
	~$setfacl -m u:priya:rw <file> #assiging the a new user 'priya' with read/write permission on the file. -m (modifying) -u (user)
	~$setfacl -m mask:r <file> #setting mask on file
	~$setfacl -d -m u:priya:rw <dir> #setting ACL for directory

### Crontab

	~$crontab -l #show crontab for all users
	~$crontab -u <user> -l #show crontab for specific user
	~$crontab -e #add cron entry in crontab file
 
### Process

	~$ps -a #all terminal 
	~$ps -e #list of all the processes
	~$ps -o #customer properties
	~$ps -ao tty,comm,pid,%mem,%cpu #<command/script> & #run the task in background
	~$ps -fp $(pgrep -d, -x logrotate)
	~$pgrep -u <userid> unison
	~$ps -p <pid> -o etime #process execution time
	~$ps -eo user,pid,ppid,%mem,%cpu --sort=-%cpu | head
	~$ps lax
	~$ps fax

### Network 

	~$dig +trace www.google.com
	~$nmcli dev status
	~$nmcli con del <interface name>
	~$ip addr show <interface name>
	~$nmcli con show
	~$nmcli con add con-name <interface name> type <ethernet> ifname <interface name> ip4 <ip address> gw4 <gateway>
	~$nmcli con up <interface name>
	~$nmcli con mod <interface name> ipv4.gateway <ip address>
	~$hostnamectl set-hostname <hostname>
	~$netstat -rn
	~$route -n
	~$tcpdump -i <interface>
	~$tcpdump -i <interface> host <ipaddress>  -nn
	~$tcpdump -i <interface> -s 0 -w <output file name example.pcap> host <ipaddress/hostname> and udp
	~$ping <hostname/ipaddress>
	~$telnet <hostname/ipaddress> <port>
	~$nslookup <domain/hostname>
	~$netstat -an |grep <ipaddress>.<port>|grep ESTAB|awk '{print $5}'|awk -F: '{print $1}'|sort|uniq -c|sort -rn #show which remote hosts make how many connection to specfic port, the output is sort on number of connections by host to port 

### Memory/Swap

	~$egrep --color 'Mem|Cache|Swap' /proc/meminfo | awk '{print $1 " " $2/1000/1000 "GB"}' #show information in GB
	~$smem -s swap -t -k -n -r
	~$smem -u -p -r
	~$free -h

### Disk 

	~$df -h
	~$df -Th
	~$du -sh <path/*>
	~$du -sch .[!.]* * | grep --regex="[0-9]*G"
	~$lsof -u <user> #list of openfiles by specific user
	~$lsof | grep delete #list of openfiles that are deleted
	~$lsof | awk '{print $1}' | sort | uniq -c | sort -r -n #sort number of open files by process

### SFTP/SCP
	
	~$sftp -oPort=<port> <user>@<ipaddress/domain>
	~$sftp -oPort=<port> -oIdentityFile=<path to key> <user>@<ipaddress/domain>
	~$sftp -o KexAlgorithms=<keyExchangeAlgo> -o HostKeyAlgorithms=<HostKeyAlgoName> -oIdentityFile=<path to key> -oPort=<port> <user>@<domain/ipaddress>
	~$sftp -oPort=<port> -o KexAlgorithms=diffie-hellman-group14-sha1 -o HostKeyAlgorithms=+ssh-dss -oIdentityfile=<path to key> <user>@<domain/ipaddress>
	~$scp -P <port> <path to src file> <user>@<domain/ipaddress>:<target path> #send the file to target system
	~$scp -P <port> <user>@<domain/ipaddress>:<src file path> <target file path locally> #fetch file from the target system

### Puppet Bolt
####For the --tmpdir flag we can use the home directory path of the remote user which will logged in on the behalf of the bolt. At some time /tmp is not executable due to which the command gets failed. (~mizz - will be confirm)


	~$bolt command run "<command>"  --no-host-key-check --tmpdir=/tmp -p <password>  --tty --targets @<ipaddress/hostname list file>  -u <user>
	~$bolt command run "<command>"  --no-host-key-check --tmpdir=/tmp -p <password>  --tty --targets <ipaddress/hostname separate by ,>  -u <user>
	~$bolt script run <script>  --no-host-key-check --tmpdir=/tmp -p <password>  --tty --targets @<ipaddress/hostname list file>  -u <user>
	~$bolt script run <script>  --no-host-key-check --tmpdir=/tmp -p <password>  --tty --targets <ipaddress/hostname separate by ,>  -u <user>
	
### Sed
	
	~$sed -n -e "/<$hostname>/,/ismail.com/ p" <targetfile> #replace the string by variable, result will be stdout
	~$sed -i -n -e "/<$hostname>/,/ismail.com/ p" <targetfile> #replace the string by variable, result will be saved in target file
	~$sed -i 's/stringtoreplace/newstring/g' myfile.txt #replace the string from the file globally

### find
	
	~$find /tmp/* -mtime +7 -exec rm {} \; #remove files from dir "tmp/" that are older than 7 days 
	~$find /home/ -type f -name ".errors*.gz" -mtime +7 -exec rm {} \; #remove files from dir "tmp/" that are older than 7 days - with filename
	~$find /home/ -type f -size +500M -name "*tempfile*" -exec du -sh {} \; #found the tempfile that has file size >500MB
	~$find /home/ -type f -size +1G -exec ls -lh {} \; | awk '{ print $9 "|| Size : " $5 }' #find output in custom defined format like in this "dirname || Size:_"

### Cool Grep

	~$cat myfile | grep -B 1 -A 4 -i 'string one\|string two' #it will show 1 line before and 4 lines after matching the strings form myfile
	~$grep -lr "string" * #search recursively the string from all filesystem hierarchy, as its start from which current dir you are standing and it will list files
	~$grep -ir "string" <* or file> #search recursively the string from all filesystem hierarchy and show the content what matches - * for all files otherwise specify a single file
	
### Additional 

	~$top -b -n 1 | head -n +5
	~$uptime
	~$sestatus #check selinux status