var=`command` # put output of 'command' into $var
var=$(command) # same as above, but can be nested. Non-standard but works in major shells
command1 | command2 # feed standard output of 'command1' to standard input of 'command2'
command > file # overwrite file 'file' with output of 'command'
command >>file # append output of 'command' to file 'file'
command < file # feed file 'file' to standard input of 'command'
# now, the handy "heredoc"
command << "MARKER" # feed everything until MARKER (can be anything, traditionally it is EOF)
blah # to 'command'. this is useful in scripts where you want to give a program
blah # some input automatically without dequiring the user to type
MARKER # :)
# the "pipe" | can be used with a variaty of UNIX programs, for example grep, sed, awk, head, tail and diff.
# redirecting output to a file ( >file ) can be used to supress output: command >/dev/null
# (the UNIX pseudo-device /dev/null swallows all input and outputs only ASCII EOF)