10 Eylül 2015 Perşembe
Linux Bash Shell Tutorial : How to use I/O redirection.5 tips and tricks
Understanding Input Output or I/O redirection works in Linux helps us streamline our job better when working with the terminal. In this tutorial,I will share quick tips and tricks on how to use I/O redirection in our system.
A few terminology that will help you understand this tutorial is as below:
Standard Input -what is being type in terminal from keyboard.
Standard output -text that display in terminal on command execution
Standard error – text that display in terminal when a command runs and exit with an error
Content List
1)Redirecting standard output to a file.
2)Redirecting a file to standard input.
3) Redirecting standard error to a file.
4)Redirecting Standard output and error to one file
5) Disposing unwanted output -/dev/null (bit bucket)
1)Redirecting standard output to a file.
Use “>” operator sign to redirect and save output file in current directory .
To append/update existing file use “>>”
2)Redirecting a file to standard input.
Use “<” operator to redirect an input to the terminal
In above example, I write new content to file stdin and redirect stdin file to the terminal using "<" sign operator.
3) Redirecting standard error to a file.
Use “2>” operator sign to redirect standard error to a new file in current directory.
To append/update existing file use “2>>”
4)Redirecting Standard output and error to one file
Use “&>” operator sign to redirect standard output and standard error to a new file in current directory .
To append/update existing file use “&>>”
 |
| file stdouterr |
5) Disposing unwanted output -/dev/null (bit bucket)
Use “2> /dev/null” operator sign to redirect unwanted output to bit bucket. Data that are redirect to bit bucket will be deleted without a trace. As such some people also call bit bucket as a black hole.
*NOTE:If you execute the same command using ">" ,"<" ,"2>" ,"&>" to same file name but with different content, the file will be overwritten with new file content .
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