| 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
Displays 10 more lines after (from the line where the text was found).
Ex: grep -A 10 boo /etc/passwd.
b). -B 10
Displays 10 more lines before (from the line where the text was found).
Ex: grep -B 10 boo /etc/passwd.
c). -C 10
Displays 10 more lines before and after (from the line where the text was found).
Ex: grep -C 10 boo /etc/passwd.
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. |
chouhans 