Cheat sheet

From WakeDEAC

This Cheat sheet lists many of the common and useful Linux/Unix commands, in case you forget.

N.B: Most commands have more flags listed; typing man "cmd" will provide additional info on command ;cmd".

Contents

[edit]

Useful commands

cd d

Change to directory d

mkdir d

Create new directory d

rmdir d

Remove empty directory d

mv f1 [f2...] d

Move file(s) f1(,f2...) to directory d

mv d1 d2

Rename directory d1 as d2 or, if d2 exists, move d1 into d2

passwd

Change password

alias name1 name2

Create command alias name1 so typing "name1" executes name2

rsh nd

Login to remote computer/node nd

ssh nd

Securely login to remote computer/node nd

ssh -n nd cmd

perform command cmd on node nd

sentenv name v

Set environment varable to value v {if this doesn't work you are in the bash shell}

man name

Manual entry for name

CTRL-c

Interrupt processes

sleep n

Sleep for n seconds

jobs

Print list of jobs

kill %

Kill job n

hostname

name of the computer you are on

ps

Print process stats

ps -u us

Print processes for user us

killall nm

Kill all processes matching name nm

kill -9 n

Remove process n

CTRL-z

Suspend current process

cmmd&

Run cmmd in background

bg [%n]

Resume background job n

fg [%n]

Resume foreground job n

df

disk space free in bytes
df -k
disk free in KB
df -h
disk free in more readable format
df -i
inodes free
df -ih
inodes free in nmore readable format
du
disk usage
du -k
disk usage in KB
du -s
summarize disk usage for a directory tree
du -hs
summarize disk usage in more readable format
exit
Exit from shell
ls [d] [f...]
List files in directory
ls -1 [f...]
List files in detail
ls -a
include dot files
ls -lh
more size readable format
ls -t
Time order files
ls -rt
reverse time order
ls -rtalh
all of the above lists
alias [name]
Display command aliases
date
Print date & time
who
List logged in users
whoami
Display current user
finger [username]
Output user information
pwd
Print working directory
history
Display recent commands
! n
Submit recent command number "n" (obtain number from history)
vi [file]
Vi editor (often system alias for vim)
wc file
Line, word, & char count for file f
wc -l file
line count only
cat file
List contents of file
cat f1 f2
Concatenates f1 & f2
cat f1 f2 > f3
into file f3
cat f1 f2 >> f3
append f1 and f2 to f3
more file
List file contents by screen
more +xxx file
list file contents by screen starting at line xxx
paste f1 f2
pastes f1 and f2 together
paste f1 f2 > f3
into file f3
paste f1 f2 >> f3
append f1 and f2 to f3
sort f
Alphabetically sort file f
sort -n f
Numerically sort f
sort -rn f
reserve numerically sort f
mv f1 f2
Rename file f1 as f2
rm f
Delete (remove) file f
rm -r d
Removes a directory d recusively
grep 'ptn' f
Outputs lines that match ptn in file f
head f
Outputs beginning of file f
tail f
Outputs end of file f
diff f1 f2
Compare two files
cp f1 f2
Copy file f1 into f2
[edit]

Chmod

chmod mode f Change permissions of f 

                       mode: y+ab
                               a=all
                               g=group
                               u=user
                       + adds permissions
                       (- substracts)
                               r=read
                               w=write
                               x=execute
                               s=sticky

chmod -R mode dir recursively changes mmode of directory

chgrp groupname file changes group of file or directory

chgrp -R groupname dir/ recursively changes group of directory

N.B. when changing group set sticky with chmod to make sure new files and directories keep the group

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Scp

scp f1 username@computer:f2 copies securely from one computer to another scp temp salsbufr@dirac.phy.wfu.edu:ARCHIVES/tmp copies the file temp from the current computer to dirac.phy.wfu.edu to the file /home/salsbufr/ARCHIVES/tmp where /home/salsbufr is the home directory for salsbufr on dirac salsbufr is also as username for authentication ( a password will be required) scp temp salsbufr@dirac.phy.wfu.edu: copies file temp to /home/salsbufr/temp on dirac. Note: the : is always needed! Otherwise, the file temp would be copied to a file salsbufr@dirac.phy.wfu.edu on the first computer!


[edit]

Wildcards with examples

  • match any number of characters; use with caution!
? match one character

Examples

rm *.e???

would delete any file having any number of characters followed by .e and then 3 characters 
ssh -n deac024 ls "/scratch/azaria0/*"
lists all files on deac024 in the /scratch/azaria0 directory. Note the "", it is to protect he wildcard so that it is expanded on deac024 .
[edit]

General control

cmd < file Take whatever is in file as input for cmd
cmd > file Put the output from cmd into file cat f1 f2 > f3, would cat f1 and f2 into file ff3
cmd >> file Append output from cmd to file

foreach n ( a b c d e ) will do a foreach loop using $n as a then b then d then d 


foreach n ( 01 02 03 04 )
ssh -n deac0$n hostname
ssh -n deac0$n ls "/scratch/salsbury/*/*" 
end
will execute the command hostname and then the ls on deac001 then deac002 and so on
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