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Linux Files and Directories
Directory commands
File commands

pwd - Display name of current directory

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

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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

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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.

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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

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Wildcards

Wildcard characters are used to help find file or directory names

Options What it does
* asterisk symbol is used to represent anycharacter(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'

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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'

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mv - Rename files

The command mv is used to rename a file

Example: mv myfile yourfile - Will rename the file 'myfile' to 'yourfile'

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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

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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

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