Command

important Option(s)

impact of the command

impact of the option(s)/remarks

cat

file

display text file contents

chgrp

<group> file

change group owner of file or directory

chmod

<options> file

change permissions for file or directory

chown

<owner> file

change owner of file or directory

cp

source target

copy file

target may be a new file name or directory

df

-k partition

display free space on hard drive

-k: values in kilobyte, dot for current directory

exit

finish terminal session/program

e.g. to finish GRASS

file

file

display file type (mime type)

displays, if file is in ASCII or binary format

ftp

hostname

file transfer via network

hostname: Internet address

grep

string file

search for string in file

string should be quoted

gunzip

file

uncompress file with ".gz" extension

gzip

file

compress file

head

-n file

display heading lines of text file

-n: number of lines to display

kill

-9 pid

remove hanging process from system

-9: force removal, find pid with ps command

lpr

-P printer file

print file on printer

ls

-l or -la

list directory's contents

-l: long, -la: hidden files as well

man

program

online manual

Usage: man program

mkdir

directory

make directory

more

ascii_file

display text file page-wise

continue with <ENTER> to next page

mv

-i source target

move or rename file/directory

source and target: new filename or directory

ps

-aef (or -aux)

display running processes

display process data, especially pid (process-ID)

pwd

print working directory

rm

-i file resp. -ir directory

remove file/directory

-i: query interactively, -r: recursive

rmdir

directory

remove empty directory

script

logfile

log session into text file

finish with <CTRL><D>

ssh

hostname

secure terminal for external hosts

hostname: Internet address

tar

xvf package.tar

extract files with directory structure

tar

cvf newpack.tar source

package directory structure

-c silently overwrites existing packages