Questions and Answers (Latest Update
2024) Verified A+
whereis used to search for programs in restricted locations, such as binary file directories,
libraries, and man directories.
locate Searches the system managed database of filenames for files containing the specified
string in the filenames. (Search is much faster than the search performed using the 'find'
command)
updatedb Updates the system managed database of filenames
Displays current working directory pwd
Change into the current user's home directory cd ~
cd $HOME
Both of these do what
Change to the parent directory of the current directory cd ..
Change to the etc directory in the root (/) directory cd /etc
Creates a hard link named 'format.txt' for the file 'fmt.txt' ln fmt.txt format.txt
Creates a symbolic link named sym.txt of fmt.txt ln -s fmt.txt sym.txt
touch Can be used to update the timestamp of a file or if that file doesn't exist it will create a
blank file with the specified name.
Will update the timestamp of the specified file if it exists. If it does not exist it will not create a
blank file. touch -c file1.txt
, Adds the content "Hey there!" to the specified file. echo "Hey there!" > sample.txt
cat filename.txt Displays the contents of a file
Opens the vi editor for the file "sample". This will allow you to write text into a file. vi
sample
Will display the "sample" file's byte count wc -c sample
Displays the number of characters in the "sample" file wc -m sample
Display the number of lines in the "sample" file wc -l sample
Display the word count of the "sample" file wc -w sample
Extracts the first field of the "/etc/passwd" file cut -f 1 /etc/passwd
Extract the first three characters from the "/etc/passwd" file cut -c 1, 2, 3 /etc/passwd
Extracts the third field from the "/etc/shadow" file and uses the : seperator. Since "/etc/shadow"
is a : (colon) seperated file, this command will display only the content of the third field in the
file. cut -d ":" -f 3 /etc/shadow
Search for all the rows containing the string "/home" in the "/etc/passwd" file grep /home
/etc/passwd
Display the number of lines containing the string "/bin" in the "/etc/passwd" file grep -c /bin
/etc/passwd
Display the details of the root user from the /etc/shadow file grep root /etc/shadow
Search the /etc directory recursively for the string "wlan" grep -r wlan /etc
Find all the files in the /etc directory having names that start with pass find /etc -name pass*
List the files in the /etc directory with extensions conf (limit the search to one level) find
/etc -maxdepth 1 -name *.conf
List all the files on system with the permission set 640 (limit the search to two levels) find / -
maxdepth 2 -perm 640
List the files in the var/cache directory owned by the root user (limit the search to two levels)
find /var/cache -maxdepth 2 -user root
find /var/cache -maxdepth 2 -uid 0
List all the files in the /root directory that belong to the root group (do not use shorthand for
specifying the directory) find /root -group root