Both the input and output of a command may be redirected:
command > filename Redirect command output into a file command >> filename Redirect command output and APPEND into a file command < filename Redirect a file into a command command | tee filename | commandB Redirect command into filename AND CommandB
The NOCLOBBER option can prevent you from overwriting an existing file
$ set -o noclobber turns ON noclobber
$ set +o noclobber turns OFF noclobber
Redirecting Input
Redirection of input causes the file whose name results from the expansion
of word to be opened for reading on file descriptor n,
or the standard input (file descriptor 0) if n is not specified.
The general format for redirecting input is:
[n]<word
Redirecting Output
Redirection of output causes the file whose name results from the expansion
of word to be opened for writing on file descriptor n,
or the standard output (file descriptor 1) if n is not specified.
If the file does not exist it is created; if it does exist it is truncated to
zero size.
The general format for redirecting output is:
[n]>[|]word
If the redirection operator is `>', and the noclobber
option to the set builtin has been enabled, the redirection will
fail if the file whose name results from the expansion of word exists
and is a regular file. If the redirection operator is `>|',
or the redirection operator is `>' and the noclobber
option is not enabled, the redirection is attempted even if the file named by
word exists.
Appending Redirected Output
Redirection of output in this fashion causes the file whose name results from
the expansion of word to be opened for appending on file descriptor
n, or the standard output (file descriptor 1) if n
is not specified. If the file does not exist it is created.
The general format for appending output is:
[n]>>word