In linux, the directory is just a pointer to the location. What we really want if the size of all the files that are contained in that directory. To see the individual sizes of all the directories inside the current directory: du -sh * the ‘s’ option provides a summary, the ‘h’ option provides the Continue reading

Format The format of the command is given below: %s/<string_being_replaced>/<replacement_string>/ Examples In order to replace the word “hate” with “love”. Open the file in vi Hit [Esc] (Esc in vi lets you type commands instead of typing content) Type : (colon) followed by %s/hate/love/ and hit [Enter] key. :%s/hate/love/ Above command will replace first occurrence Continue reading

When using xterm, if you are not able to see the display show up on your screen, or you get an error, try setting your display. Find the ip of your local windows desktop using the following command: C:\>ipconfig Windows IP Configuration Ethernet adapter Local Area Connection 6:    Connection-specific DNS Suffix  . : dev.company.gov Continue reading

The scp command in linux is used to securely copy (scp – secure copy) files and folders from one linux server to another. The basic structure of the scp command is as follows: scp source  target scp username@source_servername_or_ip:/path/to/file_or_directory location/to/copy/file_or_folder/to When you run the above command from the target directory, you will be prompted to type Continue reading

Here is a way to truncate a log file on linux: cp /dev/null file_to_truncate.log     Continue reading

To switch user when you are in the sudoers list: sudo su – username Linux will then ask you to type your password (not the user you are switching to, but the user you are logged in as). You can always do whoami to check who you are running the command as whoami   Continue reading

When doing a find command, like the following, if you do not have sufficient permissions, you will get a lot of “permission denied” messages. This sometimes drowns out the few lines where you actually get a hit. One way to avoid that is to add the following to the command: find / -name filename.txt 2>/dev/null Continue reading

To check entropy: cat /proc/sys/kernel/random/entropy_avail To increase entropy: rngd -r /dev/urandom -o /dev/random -b -t 1 Continue reading

If you need to compare two text files in Linux, try the following command: comm -23 <(sort OLDFILE) < (sort NEWFILE > OUTPUTFILE Options Explained: -1     suppress lines unique to OLDFILE -2     suppress lines unique to NEWFILE -3     suppress lines that appear in both files Continue reading