Redirection in Bash

> redirects output read from a file descriptor to a file. Default descriptor is 1 (stdout), so >name means 1>name. Example:

1

ls -a > result.txt

< redirects input. So wc < file.txt means wc will treat data from file.txt as stdin.

2>& redirects file handle “2” (almost always stderr) to some other file handle (it’s generally written as 2>&1, which redirects stderr to the same place as stdout).

&> and >& redirect both stdout and stderr to a file. It’s normally written as &>file (or >&file). It’s functionally the same as >file 2>&1. (todo: so why do they have different syntax?)

&>file is equivalent to 1>file 2>&1.

• It seems like you can ignore spacing between redirection symbols. So ls > file and ls>file are the same. But when dealing with descriptors and stuff - it should be without spaces (2>).
• Files are read/created at first and then the commands are executed. So ls > file will write file in file.

Terminal tips

• bash redirects - wizardzines
• Read and write data from anywhere with redirection in the Linux terminal | Opensource.com
• Input Output Redirection in Linux/Unix Examples
• What does &> do in bash? - Stack Overflow
• What’s the difference of redirect an output using “>”, “&>”, “>&” and “2&>”? - Stack Overflow

More advanced:

• What does the < (left chevron / triangle bracket) do?
• What does «< mean?
• What’s the difference between «, «< and < < in bash?