cat foo.tar

display the contents of a tarball

cat the blue dog does tricks > cat-output.txt

echo “the blue dog does tricks” > cat-output.txt

concatenate the input on the screen and redirect it to a file.

cat file1 file2 > file3

combine two files into a third file

grep word myfile.txt

search within a file or directory or command output for a search term

grep -r word mydirectory/

search recursively within a directory

grep -i word myfile.txt

search case insensitive

grep -e “.boo.” myfile.txt

egrep “.*boo.*” myfile.txt

search using wildcards

ls | grep myfile

search within a command output for a search term

wc myfile.txt

display the line count, word count and byte count information of a file

wc -l myfile.txt

display the line count of a file

wc -w myfile.txt

display the word count of a file

ls | wc -l

display the line count of the output of the ls command

head myfile.txt

display the first 10 lines of a file starting at the top

head -n 20 myfile.txt

cat myfile.txt | head -n 20

display the specified number of lines of a file starting at the top

tail myfile.txt

display the last 10 lines of a file starting at the bottom

tail -n 20 myfile.txt

cat myfile.txt | tail -n 20

display the specified number of lines of a file starting at the bottom

tail -f /var/log/messages

view changes to the file as they occur

ln -s mydirectory/myfile name-of-symlink

ln -s /full/path/to/original /full/path/to/new/link

create a symbolic link, like a shortcut to a file or directory

alias

list current aliases

alias foo=“cat myfile.txt | less”

create an alias for a command, like a nickname or shortcut

alias ls=“ls –color”

redefine an existing command

unalias -a foo

remove an alias

zip -rv foo.zip mydirectory

create a zip file - this directory will be both compressed and zipped extension zip

unzip foo.zip

extract a zip file - this file will be both uncompressed and unzipped

zip -sf foo.zip

unzip -l

display a list of files in the zip file

unzip -c

display the contents of a zipped file

bzip2 -v foo.txt

create a bzip2 file - this will replace the original files with a new file extension bz2 using verbose option

bunzip2 foo.txt.bz2

extract a bzip2 file - this will replace the original files with a new file

bzcat foo.txt.bz2

less foo.txt.bz2

display the contents of a bzip2 file

gzip -v foo.txt

create a gzip file - this will replace the original files with a new file extension gz

gzip -vr mydirectory

create a gzip file of a directory - this will replace the original files with a new file

gzip -dv foo.txt.gz

gunzip foo.txt.gz

extract a gzip file - this will replace the original files with a new file

ls -l /etc | gzip > foo.txt.gz

pipe the output of ls -l to the gzip command and store that in foo.txt.gz

zcat foo.txt.gz

display the contents of a gzip file

zless foo.txt.gz

display the contents of a gzip file

tar -cvvf foo.tar mydirectory

create a tarball of a directory

tar -cvvf foo.tar file1.txt file2.txt

create a tarball of a list of files

tar -xvvf foo.tar

extract a tarball

tar -rvf foo.tar file3.txt

add a file to the tarball

tar -tf foo.tar

list the files in the tar file

tar -cvvf just_tar.tar file?.txt

tar a list of files using the wildcard

tar -cvzf foo.tgz mydirectory

create a tarball and gzip it at the same time

z option send it through the gzip compression

tar -xvzf just.tar.gz

tar -xvzf just.tgz

extract a tarball and gunzip at the same time

tar -cvzf just.tar.gz file?.txt

tar and gzip at the same time a list of files using the wildcard

tar -cvjf just.tar.bz2 dirname/

create a tarball and bzip2 it at the same time

j option sends it through the bzip2 compression

tar -xvjf just.tar.bz2

extract and bunzip2 at the same time

ls -l /usr/bin > ls-output.txt

redirect standard output to a new file

ls -l /usr/bin >> ls-output.txt

redirect standard output and append to the end of a file

ls -l /bin/usr 2> /dev/null

redirect standard error to /dev/null

ls -l /bin/usr 2>> ls-error.txt

redirect standard error to a file

find /home -name ‘fun.txt’

find files by name searching within the /home directory

Find / -name *fun*

find files using wildcards to match a name searching within the root ( / ) directory

find ./ -iname *fun*

find files by name but be case insensitive searching within the current directory (using a dot-slash)

find ~ -name ‘fun.txt’

find files by name in your $HOME directory

find / -name “*fun.txt*” 2> /dev/null

find files by name and redirect the errors

find / -name *elephant* 2> /dev/null >> save.txt

find a file with elephant in the name and redirect standard error to /dev/null and redirect standard output to save.txt