THINGS YOU REALLY SHOULD KNOW IF YOU USE A COMMAND LINE
Eric Saunders, October 2007

Here is a small of the most critical commands needed to make reasonable use of
the unix command line. A small number are specific to the c-shell. This list is
by no means complete. The general rule is: if you want to do something with
files in unix, there's probably a tool to do it already, better and faster than
anything you will come up with.


*****The tcsh shell*****
CTRL-A                            Move cursor to start of line
CTRL-E                            ... to end of line
CTRL-D                            Provide a list of completions
*                                 All files, e.g. 'rm *' = 'delete all files'
|                                 'Pipe': chain two processes
>                                 Redirect output to a file
alias name command                Create an alias for command called name
.cshrc                            File for storing preferences, aliases etc.


*****History functions*****
history                           Print your command line history
!command                          Execute the last line matching command
!$                                Use the arguments of the previous command


*****Basics*****

man command                       Get useful information on command
ls                                List files in current directory
cd dir                            Move to directory dir
mkdir dir                         Create a directory called dir
rm files                          Delete files
rm -r dir                         Delete dir and all files and subdirs below
mv file1 file2                    rename file1 to be file2


*****Finding files*****
locate file                       Find matching files indexed by the system
find . -name 'file'               Find file if it exists here or in any subdir
find . -mmin -20                  Find all files modified in the last 20 minutes


*****Using text files*****
cat file                          Print the contents of file to the terminal
head file                         Print the first few lines of a file
tail file                         Print the last few lines of a file
less file                         Print file one screenful at a time
grep text file                    Find all lines that match text in file
grep -v text file                 Find all lines that *don't* match
wc file                           Get the number of words and lines in file
diff file1 file2                  Print the differences between file1 and file2


*****Packaging files*****
gzip file                         Compress ('zip') a file 
gunzip file                       Uncompress a zipped file
tar cvzf file.tar.gz files        Make a single zipped tarball containing files
tar xvzf file.tar.gz              Extract files from zipped tarball
tar tvzf file.tar.gz              Look at files in tarball without extracting

*****Managing processes*****
top                               View system resource usage (CPU, memory etc.)
ps aux                            List all processes
kill proc_id                      End the process with id proc_id
kill -9 proc_id                   *Really* end it


*****Connecting to other machines*****
ssh -Y user@machine               Log in to machine as user, with X forwarding
scp user@machine:path/to/file .   Copy file from remote machine to current dir



*****Examples*****
1) Find the size of all files in the current directory, in 'human' units.
ls -lh *

2) Print all lines in all files ending in '.dat' containing 'star08' (upper
or lower case), and print the line numbers.
grep -in star08 *.dat            

3) Find all perl code in your home directory or any subdirs.
cd
find . -iname '*.pl' -or -iname '*.pm'

4) Alias an annoyingly long log-in command to the new command 'pinky'.
alias pinky 'ssh user@pinky.astro.ex.ac.uk'

5) Find all occurences of function 'do_calc' that are not function calls in all
fortran files in the current directory, and write them to a file called
'do_calc_definitions'.

grep do_calc *.f90 *.F | grep -iv 'call' > do_calc_definitions

6) Create an alias for your .cshrc file to print the 20 most recent files in the
current directory, from oldest to newest:

alias newest 'ls -lrt \!* | head -n 20'