Advanced Bash-Scripting Guide

Advanced Bash-Scripting Guide(( ))As part of a regular expression, brackets delineate a range of characters to match.integer expansion.Expand and evaluate integer expression between (( )).See the discussion on the (( ... )) construct.> &> >& >> < redirection.scriptname >filename redirects the output of scriptname to file filename. Overwritefilename if it already exists.command &>filename redirects both the stdout and the stderr of command to filename.command >&2 redirects stdout of command to stderr.scriptname >>filename appends the output of scriptname to file filename. Iffilename does not already exist, it is created.[i]filename opens file filename for reading and writing, and assigns file descriptor i to it. Iffilename does not exist, it is created.process substitution.(command)>