====== Use Input-output Redirection ======

**General Information**

Using input/output redirection (>, >>, |, 2>, etc.).

----

'>' Redirect standard output to a file, overwrite contents
<code bash>
cat /etc/system-release > info.txt
</code>

\\
'>>' Redirect standard output to file, append to file
<code bash>
tail /etc/passwd >> info.txt
</code>

\\
'|' Piping output to other commands
<code bash>
cat /etc/passwd | wc -l
</code>
  * Counts the number of lines in /etc/passwd

\\
'2>' Redirect standard error
<code bash>
ssh admin@webserver01.com "uptime" 2>/dev/null
</code>
  * SSH to webserver01.com, issue the uptime command, send standard errors to /dev/null (to nowhere)

\\
Redirect both standard error and standard output
<code bash>
ssh admin@webserver01.com "uptime" &> results.log
</code>

\\
Redirect standard error to standard out
<code bash>
cat /etc/system-release /etc/Red 2>&1 | grep Red
</code>
  * Standard output can be passed through a pipe to the next command. By redirecting standard error to standard output, any error messages are successfully sent through as well.

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