UNIX Basics UNIX Basics CIS 218 Oakton Community College History - - PowerPoint PPT Presentation
UNIX Basics UNIX Basics CIS 218 Oakton Community College History UNIX was invented in 1969 at AT&T Bell Labs Ken Thompson and Dennis Ritchie are credited as the original architects and developers of C. Written in the C
UNIX Command Description
pwd Display current directory
cd / Moves to the root directory
cd .. Moves up one level in the directory structure
cd path Sets the current directory to a new directory
du Displays disk usage
clear Clear the screen
sh, csh .. Start a new shell (command processor)
cmp Compares two files and shows the difference
cp Copy a file
date Displays the date
rm Deletes a file
rm -r Deletes a directory tree ( CAREFUL ! ! ! )
ls -l Lists the directory in a long format
ls Lists the directory in a short format
echo Displays a message or a variable
exit End a shell
diff Displays differences between two files
grep Displays lines matching a given pattern
man Display information about a command
mkdir Creates a directory
more Displays text a page at a time
mv Moves a file
lpr Prints a file
rmdir Removes a directory
mv Renames a file
set Sets a variable to a given value
sort Sorts a data
date Displays the time
cat Displays a file
Text files - text that is “human readable”. Binary files - executable files
Symbolic or “soft” - may span file systems. Hard - is indistinguishable from the original file/directory.
File1 juliana Project File2 File3
r : indicates read permission (or otherwise), that is, the presence or absence
w : indicates write permission (or otherwise), that is, the permission (or
x : indicates execution permission (or otherwise), that is, the permission to execute a file, where appropriate
r : allows users to list files in the directory; w : allows users to delete files from the directory or move files into it; x : allows users the right to access files in the directory (e.g. cd into directory), read files in the directory provided you have read permission on the individual files.
Symbol Meaning u user g group
a all r read w write (and delete) x execute (and access directory) + add permission
db5-24 nwade.txt schumacher5-19.txt kirsh5-12.txt nwade5-13a.txt sheu5-20.txt
find . -name ‘*name*’ –print –exec “cmd” {} \;
– Use them whenever you need to define a string of characters, such as a filename, for use with a command.
* matches any characters, zero or more. ? match any single character. [...] matches any character in the enclosed list or range. Examples:
– ls *.txt # Lists all the files in the current directory # that have the extension .txt. – cat memo? # Concatenate files that start with “memo” # and are followed by any one character. – rm part[1-3] # Remove files: part1, part2 and part3