Fundamental Unix Commands
From DreamHost
The following are some basic commands which may be useful in the Unix/Linux shell.
To learn how to use them effectively, take a look at LinuxCommand.org.
id
print real and effective UIDs and GIDs for user’s terminal
who
displays a list of users currently logged on to the system
date
print the system date and time
passwd
update a user’s authentication token(s); change password
echo
displays a line of text
write
send a message to another specified user
mesg [ y : n ]
mesg – controls write access to your terminal by others
pwd
print name of current/working directory
ls
list directory contents
find
search for files in a directory hierarchy
mkdir
make directories
rmdir
remove empty directories
file
determine file type
cat
concatenate files and print on the standard output (usually screen)
more
file filter for paging through text one full screen at a time
man
formats and displays the on-line manual pages
tail
display the last few lines of a file
head
display the first few lines of a file
cp
copy files and directories
mv
move (rename) files
ln
make links between files
rm
remove files or directories
chmod
change file access permissions
touch
change file timestamps
chown
change file owner and group
chgrp
change group ownership
su
run a shell with substitute user and group IDs; switch user
newgrp
log in to a new group
vi
VI Text Editor
whereis
locate the binary, source, and manual page files for a command
sort
sort lines of text files
grep
print lines matching a given pattern
wc
print the number of bytes, words, and lines in files
> - redirection symbol
create a new file or overwrite an existing file by attaching it to a command that produces output.
>>
used to append output to an existing file without overwriting that file
cut
remove sections from each line of file
tr
translate or delete characters
tee
read from standard input and write to standard output and files
pr
convert text files for printing
ps
report process status
nohup
run a command immune to hang-ups, with output to a non-TTY
nice
run a program with modified scheduling priority
kill
terminate a process
tar
the GNU version of the tar archiving utility
cpio
copy files to and from archives
ftp
user interface to the standard File Transfer Protocol
telnet
used to communicate with another host using the TELNET protocol
rlogin
starts a terminal session on a remote host host
hostname
show or set the system’s host name
rlp
remote file copy
clear – And Ctrl + L
clear the terminal screen
sleep
delay for a specified amount of time
cal
displays a default or specified calendar
pg
page to control screen scrolling
diff
find differences between two files
