Basic UNIX Commands
Directory commands
cd Change the working directory
find Find a file by name or by other characteristics
mkdir Make a directory
rmdir Remove a directory
File manipulation commands
cat Concatenate and display a file
head
tail
chmod Change the permissions mode of a file
chown Change the owner and/or group of a file
cp Copy a file
diff Display differences between pairs of text files
grep Search a file for a specific text string
mv Move or rename a file
rm Remove a file
Display commands
date Print the date and time
finger Display information about a user
head Display the first few lines of a file
less Browse a text file
ls List the contents of a directory
man Display a reference manual page
more Display a text file
pwd Display the working directory pathname
tail Display the end of a file
who Display who is on the system
w
last
Process commands
exit Terminate a process
kill Terminate or send a signal to a process
passwd Create or change a password
ps Display the status of a process
telnet Connect to a remote system using the Telnet protocol
logout
File/Directory Manipulation
Manipulating
files and Folders in Unix
chmod - change file modification rights
Format
chmod abc filepath
Summary
Changes rights of the file to owner=a, group=b, world=c. Example: 777
=
read/write/execute rights for all, 750 = full rights for owner, read/execute
rights for group, no writes otherwise. Numbers are formed by adding 4
for
read, 2 for write, and 1 for execute.
chown - change owner
Format
chown user:group filepath
Summary
Changes owner and group of the specified file/folder to owner and group.
cp - copy one or more files
Format
cp [options] source-file destination-file
cp [options] source-file-list destination-directory
Summary
The program has two modes. You can copy one file into another. Or copy
a
file from one place to another.
You can use wildcards * and ?.
Options
-r Copies directories recursively. With this i mean
that all files
including subdirectories and their content given by source-file-list will
be
copied to the destination directory.
df - disk free displays the amount of available disk space
Format
df [options] [filesystem-list]
Summary
If you don't specify the filesystem-list, df will list the amount of
available disk space on all mounted filesystems
Options
-t type, causes df to display information about the type of the filesystems
of the specifies type.
du - disk used
Format
du [directory-list]
Summary
Lists the diskspace used by the directory and its contents specified by
the
directory-list argument
find - find a file
Format
find directory expression
Summary
directory specifies the directory where you want the search to start.
Find
will search all directories recursively.
expression is the search argument. These are the most common used:
Search arguments
-name filename, searches for the given filename
-user name, list all files who are owned by the
given users
-size +/-n, lists all files with size smaller/greater
than n
-maxdepth n, searches no more than b directories down from current
location
ln - make a link to a file
Format
ln [option] existing-file new-link
Summary
Creates a hard link to the file specified by existing-file with the name
given by the new-link argument. A hard link to a file is indistinguishable
from the original. A hard link has to be on the same filesystem as the
original file. A symbolic link may be across filesystems and existing
file
and new-link may be directories as well as files.
Options
-s creates a symbolic link instead
locate - locates files
Format
locate pattern
Summary
Lists all files in filedatabase that match the given pattern.
This utility depends on a database file with al list of all files on your
filesystem. Use the updatedb utility to update your database (caution,
this
takes a while)
Example
#locate hepp
This search would find all files on yor system that contain hepp. It would
find heppgr, tghepp and tyheppl.
mkdir - make directory
Format
mkdir [options] directory-list
Summary
Creates a new directory. If you write #mkdir test, mkdir creates a new
directory with the name "test" in the current directory.
If you want mkdir to make a directory in another directory, you must specify
the whole directory path.
Options
-p parent, if the parent directory of the directory you are creating does
not exist, mkdir will create it for you.
mv - move files
Format
mv [options] source-path destination-path
Summary
Copies the the files specified in source-path to destination path and
then
deletes the original files.
You can use wildcards * and ?.
passwd - change password
Format
passwd
Summary
Enter current password, then new password twice for verification.
pwd - path/which directory
Format
pwd
Summary
returns the full path to the current location, such as
/home/users/smith/backups
rm - remove files
Format
rm [options] file-list
Summary
This utility removes files from your system. You can use wildcards * and
?.
Note: when you delete a file it is not possible to recover it.
Options
-r recursive, this option makes rm remove the
specified directory and
all of its contents. (MS USERS: Just like deltree) BE CAREFUL WITH THIS
COMMAND!!
-f force, this option makes rm delete files without
asking you if you
really want to. Nice if you want to delete directories.
rmdir - remove directory
Format
rmdir directory-list
Summary
Removes all directories specified by directory-list.
Note: The directories you want to delete must be empty. If they are not,
mkdir will fail. If you want to delete a directory together with its
contents use rm.