Section 1
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Last updated
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Date created
Mar 1, 2020
Cards (256)
Section 1
(50 cards)
du
display a list of directories and the disk space in blocks (512 chars) they occupy
tr -s "p"
make all instances of pppppppp or pppppp or pp simply p
diff file1 file2
compare two files line by line
cd
go to a different directory
cut -d ':' -f3 filename
cut out the third field that is separated by a colon :
cut -c2
cut out the second character
chown
change the owner of the file
cd ..
go to the parent directory
tail -5 fileName
return last 5 lines of file named 'fileName'
head -c12 anotherFile
return the first 12 characters of a file named 'anotherFile'
[:alpha:]
represents letters with translate tr
ln curFile linkedFile
hard link a file
file ../*
show all the files in the parent directory and their types
dirname
removes the file's base name and returns the RELATIVE path
What is Unix
A multi-user, multi-tasking Operating system
cut -c-5
cut first five characters
find -name someFile
get the relative path from the current directory of someFile
cat
concatenate files - print to standart output
sort filename
sort a file
wc -l
get the number of lines of a file
echo -n
write to screen...omit newline chars
wc -m
get the number of characters of a file (**includes carriage return on echo) i.e subtract ONE!
find someFile
list someFile and the path of all of its subfiles starting from someFile/
grep -w
search for a word in a file
tr -d [z] someFile
delete all the z's from a file
cp
copy files AND directories
grep -c stuff filename
get the count of the number of lines of a file containing 'stuff'
basename
removes the path and returns just the name of a file
tr -d [k-m] someFile
delete all k,l and m's from given file
grep
search for a string in a file
tr ":" " "
change colons to spaces in a file
wc -c
get the number of bytes of a file (**includes carriage return on echo) i.e. subtract ONE!
[:digit:]
represents numbers with translate tr
cmp file1 file2
compare two files byte by byte (returns first position where files differ)
grep -v
search for the inverse of what you want in a file
cut -c 3-7
cut third to 7th characters
grep -i
search for a string in a file case insensitive
ln -s curFile softFile
soft link a file
wc -w
get the number of words of a file
head -5 someFile
return the first five lines of file named 'someFile'
wc someFile
display the 1) number of Lines 2) number of words 3) number of bytes and the 4) name of a file
sort -r filename
sort a file in reverse order
head
retrieves beginning 10 lines of a file
tr [:upper:] [:lower:]
change all uppercase letters to lowercase in a file
chmod
change permissions
sort -t ":" -k4 someFile
Like cut, but uses a delimiter to get fields 4,5,6...... which are ALL used to sort the file
u o g a +x -x +r -r +w -w
users others group all - change execute, read and write privilages
find anyFile
find 'anyFile' in the CURRENT directory and the path of its subfiles from 'anyFile'
echo -e
write to screen... see the escape characters
, \t etc.
sort -t ":" -k2-6 someFile
like cut, but uses a delimeter to get only fields 2, 3, 4, 5 and 6 for sorting the givenFile
Section 2
(50 cards)
date
retrieve the system date and time
export
creates an environment variable only for current instance of shell
ls -i
show inodes of files
bc
calculator
test
performs logic or conditions
bg jobNumber
move a job to the background
sh
run a script in the default shell
rm -i
interactively delete a file
touch
create a new file
mv
rename a file
sleep 20 ctrl-c
start sleep timer, but kill the process
eval
run through commands twice for evaluating variables
ctrl-z
suspend a current job
printenv
list environment variables other than env
export
create an environment variable
ctrl-z
pause a process and send it to the background
mv
move a file OR a directory
let
perform integer math
sleep 20 ctrl-Z
start sleep timer, but pause it in the background
mv
rename a directory
rm -i
prompt deletion of a file
kill %jobnumber
terminate a job
ls -a
show hidden files
ls -r
show a reverse order of files
rmdir
remove a directory
sleep 20 &
have program sleep in the background for 20 seconds
rm -r
remove a directory without using rmdir
tree
diplay the directories as a tree
&
continue a process running in the background
hard link
corresponding files updated if moved
ls -l
show all details of files
ls -R
show a recursive list of files (include subdirectories)
` `
evaluate an expression without using $( )
stat -c%i bin
get the inode for bin
kill processId
terminate a process
finger username
get information on a user - login name, name, directory, shell, mail, plan how long on system
clear
clear the scren
fg jobNumber
resumes a job in the background
stat bin
get filename, size, blocks. IO block, file Type, Device info Inode, number of links, access, modify and change time
test
same as [ ]
bc
perform floating point math
mkdir
creat a directory
ctrl-c
terminate current job
" "
escapes metacharacters - variables interpreted
readlink -m someFileName
get the Absolute path of a file including the file name
rm -r
delete a file and all its subdirectories
&
start a command running in the background
env
show the environment variables
' '
escapes metacharacters - nothing interpreted
sleep 11
cause script to pause for 11 seconds
Section 3
(50 cards)
which
find the full path of a command
' '
always a literal
$USER
user i.d. of person currently logged on
$PATH
list of directories the command line interpreter will search when you enter a command
xargs
access a variable amount of arguments
alias dir='ls -l'
run ls-l by typing dir
$[5+9]
integer math
[a-z]
look for one character in a-z globbing
[[regex]] =~
regex in conditional logic statements
whoami
show user currently logged on to the session
.
regex match only one character
users
show who is logged on by login name
[a-z]
regex match any one lower case letter
globbing
pattern matching file searching
+
regex extended match ONE or more of previous
$HOME
path to the user's home directory
[x]
look for x globbing
L{n,m}
regex extended match between n and m occurrences of L
[^bd]
look for all chars except b or d globbing (do not use !)
X*
regex match ZERO or more occurrences of previous (i.e. X)
$touch file{1,2,3}
create file1 file2 and file3 in one command
^
regex match the start of line
L{n}
regex extended match exactly n occurrences of L
[...]
regex match any of a set of chars once
? globbing
globbing match any single character MUST be a character
[!bd]
look for all chars except a or g globbing (do not use ^ )
let
integer math withouth $(( )) or $[ ]
' ! $ ; * &
regex chars require escaping to use as a literal
[0-9]
regex match any one digit
bc <<< "scale=9; 18.26/14.75"
floating point division to 9 places for 18.26 div by 14.75 WITHOUT using echo
"scale=9; 18.26/14.75" | bc
floating point division to 9 places for 18.26 div by 14.75
" "
expands variables
* globbing
globbing zero or more characters
X|Y
regex extende match X or Y
[^...]
regex match the opposite of the set of chars
L{n,}
regex extended match n or more occurrences of L
{ , , ,}
match a list of options
!!
at command line only - history of commands and aliases
~
path to the user's home directory
grep -E
option for extended grep
who
show who is logged on date and time
export
create environment variables
"scale=3; 5/2" | bc
floating point division to 3 places for 5 div by 2
+ {} () \ |
regex extended operators
$((2-4))
integer math
w
show who is logged on and what they are doing
tokens
pieces of sequence in parcing
$SHELL
stores the name of the shell you are using
egrep
command for extended grep
[A-Z]
regex match any one Upper case letter
Section 4
(50 cards)
for i in a x Name 10 do done
loop through a list
-gt
numeric greater than
-s
flag to see if exists AND has non-zero size i.e exists and is NOT empty
~+
current directory
clear
clear the screen
$var != 'Steve'
string comparison not same string
Sh-Bang! #!/bin/bash #!/bin/ksh
how all scripts begin
$0
name of the script
&&
logic AND
-n
flag to see if a STRING is not empty
-z
flag to see if a STRING has zero length
for ((i=1;i<10;i++))
iterative loop
||
logic OR
$(command)
how to refer to the value sent to standard output by a command
continue
jump to top of loop without executing rest of commands beyond that point
getopts
recognize arguments starting with - as options
case $somevar in a) do something ;; b) do something else ;; *) default something ;; esac
case statement
$1
first parameter
-lt
numeric less than
$?
holds exit or return status of previous command executed
$(command)
command substitution syntax
$var = 'some string here'
string comparison same string
function doThis() { }
function
-x
flag to see if exists AND is executable
read -n1 -p "Press any key to continue"
get only one character from user
[ ] single square brackets
syntax for logic using if, while or until
$OPTIND
first non option argument
while getopts abc varName do case $varName in a) ;; b) ;; c) ;; \?) ;; for anything else esac cone
getopts
~-
last directory you were in
-le
numeric less than OR equal
~
home directory
#!/bin/bash
Sh-Bang!
$var -eq 728
numeric comparison for equal values
tput cup x y
move the cursor to coordinate x,y
$(( $(command) + 1 ))
sum arithmetic where a command is one of the values to be added
-f
flag to see if it is a regular file
-ne
numeric NOT equal
-ge
numeric greater than OR equal
break
exit a loop
read -p "prompt: " var
store user input in a variable named var
-e
flag to see if file OR directory exists
shift $(($OPTIND-1))
move to first argument after the options
while [ ] do done
while loop
-d
flag to see if exists and is a directory
stty
change and print terminal line settings
test
syntax for logic NOT using [ ] single brackets
sh
execute a script not set up with sh-bang
until [ ] do done
until loop
if [ ] ; then elif [ ] ; then else fi
if statement
-r
flag to see if exists AND is readable
Section 5
(50 cards)
kill $!
kill the last background job
:8 within vim
send cursor to beginning of line 8 in vim
x within vim
deletes the current character in vim
uname -a
find what operating system your unix is running on
mkfs
make a new file system
:%s/old/new/gc
search,confirm and replace all occurrences in the file in vim
D within vim
delete the text from the cursor to the end of the line in vim
ZZ within vim
save your work and exit vim
var=$(ls -l)
command substitution
mesg
restrict incoming messages
:s/old/new/g within vim
search and replace all occurrences on current line in vim
dw within vim
delete the current word in vim
text
how are all variables in bash
4gg within vim
move to line 4 in vim
U within vim
undo all changes to the current line in vim
tee
read from stdin and write to both stdout AND to files
A within vim
append to the end of the current line in vim
:wq within vim
save your work and exit vim
R within vim
enter replace mode in vim
${var}.txt if var=bin then returns bin.txt
delineate a variable
>
redirect standard output to a file replacing the file
2
stderr
1
stdout
> /dev/null
get rid of output you don't want
$
syntax for referencing variables
:nohlsearch within vim
turn off highlights in vim
2>$1
redirect stderr to stdout
u within vim
undo last change in vim
${myArray[2]}
get the third value from myArray
i within vim
insert mode
/abigail within vim
highlight the word abigail throught your vim file
G within vim
move to the end of the file
0
stdin
some command <<< hello
Here string
dd within vim
delete the current line in vim
${someArray[*]}
get all the values from someArray
${#var}
get the length of the contents of var
:q! within vim
exit vim without saving
array=(x y z j k)
declare an array containing x,y,z,j,k
echo -n $var | wc -c
get the length of the contents of var without using ${#var}
:s/old/new within vim
replace all occurences of 'old' with 'new' in vim
1>$2
redirect stdout to stderr
echo 'hello' | tee f1 f2
send hello to stdin and to files f1 and f2
a within vim
append after the cursor character in vim
>>
append standard out put to the end of a file
r within vim
replace one character (returns you to command mode) in vim
tput
initialize a terminal or query terminfo database
I within vim
insert at end of the current line in vim
8gg within vim
send cursor to beginning of line 8 in vim
gg within vim
move to the top of the file in vim
Section 6
(6 cards)