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Shell I/O Redirections

>file

direct standard output to file

>>file

append standard output to file

<file

take standard input from file

p1|p2

connect standard output of program p1 to input of p2

^

obsolete synonym for |

n>file

direct output from file descriptor n to file

n>>file

append output from file descriptor n to file

n>&m

merge output from file descriptor n with file descriptor n

n<&m

merge input from file descriptor n with file descriptor n

<<s

here document: take standard input until next s at beginning of a line; substitute for $, `...`, and \

<<\s

here document with no substitution

<<'s'

here document with no substitution