Linux Files and Directories

pwd - Display name of current directory

The command pwd is used to display the full path name of the current directory.

cd - Switch to another directory To switch to another directory, the command cd is used. Examples What it does cd Will place you in your home directory cd / Will move you to the root directory cd /etc Will move you to the /etc directory cd ../ Will move you back one directory mkdir and rmdir - Create/Delete directories The command mkdir is used to create a new directory. The command rmdir or rm -r is used to delete a directory or directories. Be careful in testing the following delete commands. You will probably want to create sample directories first. Examples What it does mkdir mydirectory Will create a new directory named 'mydirectory' rmdir existingdirectory Will delete the existing directory named 'existingdirectory' rm -r existingdirectories Will delete the existing directory named 'existingdirectories' and all directories and files below it. ls - List the Contents of a directory The command ls is used to the contents of a directory. Options What it does -l long listing -R list current directory and all other directories within current directory -a list hidden files -CF list in column format and append '*' to executable files, '@' to symbolic linked files, '/' to directories -r list in reverse alphabetically order -t list more recent accessed files first filename(s) Values to match Examples What it does ls only list file/directory names in current directory ls -l list all file/directory information in current directory(long version) ls -R list all files in current directories and below ls -lt list all files, sorted by most recent accessed first ls -lt /etc/rc* list files in the '/etc/ directory, only starting with 'rc' and sort results by most recent Wildcards Wildcard characters are used to help find file or directory names Options What it does * asterisk symbol is used to represent any character(s) ? question mark is used to represent any single character [from-to ] Values entered within square brackets represent a range (from-to) for a single character [!from-to ] Values entered within square brackets represent a range (from-to) to exclude for a single character Examples What it does a* all files starting with the letter 'a' *z all files where the last character is a 'z' a*m all files that start with the letter 'a' and end with 'm' th?? all files that start with 'th' and are only four characters long [a-c]* all files that start with 'a, b or c' x[A-C]* all files that start with the letter 'x' and the second character contains 'A, B or C' [!M-O]* all files except those that start with 'M, N or O' cp - Copy files To copy a file, the command cp is used Example: cp oldfile myfile - Will copy the existing file 'oldfile' to a new file 'myfile' mv - Rename files The command mv is used to rename a file Example: mv myfile yourfile - Will rename the file 'myfile' to 'yourfile' rm - Delete files Examples What it does rm myfile remove the file 'myfile' rm -i abc* prompt to remove each file in current directory starting with 'abc' rm abc* remove all files in current directory starting with 'abc' automatically wc - Count the number of lines or characters The command wc is used to count lines, words or characters in a file or piped results from another command. Options What it does -c Number of characters -w Number of words -l filename file name(s) to use Examples What it does wc /etc/sendmail.cf Lists the number of lines, words and characters in the file 'sendmail.cf' ls /etc | wc -l Lists the number of files and directories in the directory 'etc'

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file - Display Type-of-File Description

Files can consist of several types. The command file is used to display a description for the type.

Example: file a* will list all files in the current directory that start with the letter "a" and provide a description for the file type.

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cat - concatenate files

The command cat is a multi-purpose utility and is mostly used with TEXT files.

• Create a new file and optionally allow the manual entry of contents
• cat >[filename]
• Example: cat >myfile will create a file named myfile and allow you to enter contents.
• Press Control-D to exit entry mode.
• WARNING: If "myfile" already existed, this command would replace the old file with the contents of the new file.
• Combine text files
• cat file1 file2 >newfile - This will combine file1 and file2 into newfile.
• Dissplay the contents of a file
• cat myfile
• Delete the contents of a file
• cat /dev/null >myfile