unix

Within a directory, what must each name be?

Within a directory, each name (file or directory) must be unique (UNIX is case sensitive tho)

UNIX root node

/

Within a directory, what must each name be?

Within a directory, each name (file or directory) must be unique (UNIX is case sensitive tho)

UNIX root node

/

what does . refer to in any directory?

itself

what does . . refer to in any directory?

the parent directory

pwd

present working directory, returns what directory you are in

cd

change directory. with no arg, goes to home directory, else, goes to arg

mkdir

make new directory (mkdir newdirectory)

mv

move (renames file or directory) (mv oldname newname) (also move files (mv filename directoryname))

ls (ls -l) (ls -a)

lists contents of directory (lists w detail) (lists even hidden ones)

date

prints current date and time

touch

Reset the modification date and time of a file to now (if file does not exist, creates new one) (touch filename)

cp, cp -r

Copy a file: cp filename copyoffile. copy a directory: cp -r dirname copydir

rm

Remove. Delete a file: rm filename

rmdir

Remove empty directory. Delete a directory (which needs to be empty): rmdir dirname

cat

Concatenate. Print out the contents of a file: cat filename

head

Print out the first lines of a file: head filename

tail

Print out the last lines of a file: tail filename

more

Print out the contents of file one screen at a time: more filename

less

Print out the contents of file one screen at a time: less filename. Like more, but allows backward movement.

man

Manual. Displays the online manual page for the given argument

cd ~, cd .., cd -

home directory, parent directory, last directory you were in

cp -r

cp -r directoryname copyname (makes a copy of a directory )

rm -i

asks for permission before removing

rmdir -r

removes any directory even if not empty

tail/head -n 5 filename

prints out first five lines of filename

echo –args–

just prints whatever args is

–args– > filename

puts the stdout of args into filename (rewrites filename)

–args– » filename

adds to filename on newline

wc filename

returns the number of lines words and characters in filename

wc (no args)

you type what you want, press CNTRL + D, returns number of lines words and characters you wrote

<

pipes in stdin or whatever

arg1 | arg2

pipes stdout of arg1 into stdin of arg 2

wc < filename

returns word count of filename

?

when used in a filename, stands for any character

*

stands for any length string of characters

- -

doesn’t eval next thing

diff file1 file2

displays the differences between file1 and file2. > is things in file2. < is things in file1

grep string file

search for “string“ in file

ls | grep html, cat file1 file2 | grep ‘hello world‘

use grep to find all html files, use it to find all instances of ‘hello world‘ in file1 file2

file file1

determines type of file1

whoami

print out username

id

it prints out the id numbers related to your username and group, and then it prints out all groups that you are in. ex:

uid=25324708(ehs72) gid=25324708(ehs72) groups=25324708(ehs72),20166(202501_cpsc.201.01-student)