Command | Description |
---|---|
sudo dscl . list /Users uid | Lists all the users ids |
sudo dscl . list groups gid | Lists all the group ids |
id -u id -u RakeshChouhan |
Gives the UID (user id) of username RakeshChouhan — Output is 502 |
dig rakeshchouhan.com | Queries DNS and displays the given domain’s ip address in the terminal. |
nl | Gives the number of lines the file has. |
export | Used to Set Environmental variables |
sudo | Execute a command as another user |
sudo -i OR sudo sh | Log in as root |
exit | switch back to RakeshChouhan |
ssh-keygen -R localhost | Removes latest added ssh key and retains the old one. |
ssh localhost | Shows the last ssh login |
ssh-keygen -t rsa -P “” | Generates a SSH key (id_rsa.pub) |
sudo chmod 700 /etc/ssh_host_dsa_key | Changing permissions to ssh_host_dsa_key |
cat $HOME/.ssh/id_rsa.pub >> $HOME/.ssh/authorized_keys | copies the generated id_rsa.pub to authorized_keys in .ssh folder |
cp | copies a file from source and pastes in the destination folder. |
ln -s | Sets the link for the given fileName to the destination folder where the given filename exists |
ps aux | less | Shows all current running process ids, with % of memory usage |
ps | Shows all current running process ids at current instance |
ps -ef | Shows all running process and as well monitor and refreshes the result in each interval |
lsof | Shows all processes and PID’s |
mkdir | Creates a directory for the given name. |
kill 12345 | Kills the process id |
jps | Shows all current running Java Processes |
man | Shows the manual page that you want to see |
echo $JAVA_HOME | Shows the current mapped JAVA_HOME environment variable |
echo $HADOOP_HOME | Shows the current mapped HADOOP_HOME environmental variable |
echo $PATH | Shows the system PATH variable |
clear | clears the current working terminal screen |
java -version | Gives the java version |
hadoop version | Gives the Hadoop Version |
pwd | Shows the current working directory |
exit | Ends the Terminal’s process |
find -f macos | Finds the file named macos in the HardDisk |
find . -type d | grep {directoryName} OR find / -name {directoryName} -type d |
Finds the directory named {directoryName} in the HardDisk |
rm -R -i | Removes/Deletes each file and each sub directory from the given directory Name with a prompt for each file and sub directory |
rm -rf | Removes/Deletes all files and sub directories without a prompt. |
rmdir | Deletes the given directory |
ls | Lists out the Non hidden files and directories in the current folder |
ls -a | Lists out all the hidden and non hidden files and directories in the current folder |
ls -l | Lists out all non hidden files and folders alphabetically, and shows the file and directory permissions,user,created date. |
ls -help | Lists out all the non hidden files and folders with more details (Users, Groups, Access levels) |
ls -l file.txt; echo $? | Check if the file.txt is present or not in a particular directory. |
wc | Displays the Counts of lines, words, bytes in this order for the given fileName |
cd | Change Directory |
cd ~ | Go to previous directory |
du -sh | grep G | Determines the Disk Usage in GB. |
tar -xvfz | Un-tars filename |
vi | Opens file with vi editor tool. |
jar -cvf WAR_NAME.war * | Creates a war for the given folder (Note that you should be in that folder for that folder to be war) |
grep ‘{WORD_TO_FIND}’ ‘{IN_FILE}’ | Searches a text in the file. Ex: grep boo /etc/passwd. See grep for more options. |
grep {GREP_OPTIONS} ‘{WORD_TO_FIND}’ ‘{IN_FILE}’ | Searches a text in the file. If using grep option
a). -A 10 b). -B 10 c). -C 10 See grep for more options. |
what is | Gives What is What. What Does What ???? |
touch | Creates a text file |
cat > {fileName} | Creates a fileName and opens it for edit/writing. “control + z” saves the file and returns. |
mv | Moves a file from Source location and drops in destination location |
rmr | Removes the mentioned file from the destination location |
ifconfig | Gives the ip, mac addresses |
netstat | Gives the network status |
netstat – a | grep “10123” | Determines which remote hosts are connecting to your host on a particular port say 10123 |
nslookup | Determines your hostname and IP and viceversa |
uptime | Determines from how many days your server is up |
stat | Displays the fileName attributes/properties |
sudo -s launchctl load -w /System/Library/LaunchDaemons/ftp.plist | Loads FTP Server |
sudo -s launchctl unload -w /System/Library/LaunchDaemons/ftp.plist | UnLoads FTP Server |
sudo apachectl start | Starts MacOSX default Apache Server |
sudo apachectl stop | Stops MacOSX default Apache Server |
sudo apachectl restart | ReStarts MacOSX default Apache Server |
httpd -v | Gives the current Apache version |
head -5
test.txt |
Prints/Displays the first 5 lines of file test.txt |
sed ‘5,$d’ test.txt | Prints/Displays the first 4 lines of file test.txt — sed is the text editor same as vi editor. |
tail -5
test.txt |
Prints/Displays the last 5 lines of file test.txt |
sed -n ‘$p’ test.txt | Prints/Displays the last 4 lines of file test.txt — sed is the text editor same as vi editor. |
head -5 test.txt | tail -1 |
Displays/Prints the 5th line from file test.txt |
sed -n ‘4 p’ test |
Displays/Prints the 5th line from file test.txt using sed editor |
grep -c “Unix” | Counts the number of times the word ‘Unix’ occurs in the given file |
sed s/Unix/UNIX/g | Replaces the word containing ‘Unix’ with ‘UNIX for the given filename |
cut -f3 | Gives only phone numbers, if my filename has tab separated Name, Address and Phone numbers. |
awk -f3 | Gives only phone numbers, if my filename has tab separated Name, Address and Phone numbers. |
exit -1 | Logout and Fail a Shell Script programatically. |
chown | Change file owner to the given userName of a given filePath |
chgrp | Change file groupName for the given fileName |
sudo chattr +i/-i | Change advanced file attributes. |
/usr/sbin/system_profiler SPHardwareDataType | grep Memory | Shows RAM memory (16GB) |
df -h | Determines how much space is left in current drive. Determines Configured SWAP space. Swap files are created in (/private/var/vm) directory. |
uname -p or arch | Displays the processor type. (Current Processor architecture type is i386) |
uname -a | Displays the type of OS running on top of UNIX. (Here Darwin) |
sw_vers | Shows the Operating Systems version. |
gcc -v | Determines whether the required version of gcc is installed |
ping or telnet | Determines if a remote host is alive or not |
top | Determines which process is taking how much CPU |
telnet hostname port | Check if a particular process is listening on a particular port on remote host. |
sudo scutil –set HostName rakeshchouhan.com | Sets the hostname (HostName is case sensitive) |
hostname | Gives you the hostname (case-sensitive). This is the same command in Windows. Also, you can “echo %COMPUTER_NAME%” in Windows to get the hostname. |
sudo lsof -i -P | grep 8001 | gives the process id of the application which is using port 8001 (PID is 3rd from the left) |
unzip -t file.zip | Determines if a Zip file is corrupted. |
unzip -j file.zip | Unzips a Zip file. |
echo “unix” | rev | Reverses a string. From unix to xinu |
echo “C for Cat” | rev | cut -f1 -d’ ‘ | rev | Gets the last word from a line in Unix file. Explanation: The entire line is reversed (taC rof C), then we cut the first word, we get (taC) and reverse it again. |
sysctl -n machdep.cpu.brand_string | Gives Processor information ex: Intel(R) Core(TM) i7-3820QM CPU @ 2.70GHz |
system_profiler | Gives all the information related to PC (Camera, Bluetooth, Processor, Memory, Wireless, etc..) |
sytem_profiler SPHardwareDataType | Gives Hardware Overview Informations. |
sysctl -a | grep machdep.cpu | Gives all CPU related information |
find / -name .DS_Store -delete | This deletes all .DS_Store files from all folders of MAC OSX file system. |
curl -O http://www.interior-dsgn.com/apache/maven/maven-3/3.1.1/source/apache-maven-3.1.1-src.tar.gz |
Downloads apache-maven-3.1.1-src.tar.gz |
sudo ln -s /Library/Java/JavaVirtualMachines/jdk1.7.0_45.jdk /System/Library/Java/JavaVirtualMachines/1.6.0.jdk |
Set a different Java Virtual Machine |
sudo apachectl start | Starts apache2 server (verify http://localhost) |
sudo apachectl stop | Stops apache2 server |
brew update | Use brew to install packages. This command updates brew formulae’s |
brew install {packageName} | Installs brew packages. Ex: brew install apache-spark |
watch -n1 ls | Watches the folder every one second. This is useful to keep a continuous watch on any folder, instead of typing ls -l on the folder every time. In order to watch for every 5 seconds for a given folder, use “watch -n5 ls” Note that ‘watch’ command isn’t available implicitly. So we need to brew it before. Ex: brew install watch |
nc -l 8081 | NetCat tool to allows clients to read from or write to network connections using certain protocols. In this case the client will be listening to port 8081. Note: -l stands for listen |
nc 127.0.0.1 8081 | NetCat tool to allows clients to read from or write to network connections using certain protocols. In this case the client will be writing to 127.0.0.1 host at port 8081. |