r1 - 20 Oct 2009 - 14:28:42 - SusieBurdettYou are here: Astrophysics Wiki >  WelcomeToExeter Web  >  TeamInfo > HowTo > BasicShellCommands

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


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'

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