Redirecting program input and output in Linux and Windows

 
When working with console applications redirecting of program input and output is a must. It is used for piping one program's output to another's input, generating files with output for further examination and so on. Every program has three standard streams - one for reading input data (STDIN), one for output data (STDOUT) and one for outputting errors (STDERR). Here are a few examples how it's done on both Windows (cmd) and Linux (bash) interpreters.  

Bash


Redirecting ls output to grep input:
 
ls -al . | grep -v notneeded
 
Reading grep input from file.txt
 
grep word_to_find < file.txt
 
Redirecting gcc output to out.txt and errors to err.txt
 
gcc source.c >out.txt 2>err.txt
 
Redirecting both output and errors to file out.txt
 
gcc source.c 2>&1 >out.txt
 
Append both output and errors to file out.txt
 
gcc source.c 2>&1 >>out.txt
 
Paging results from find output using more
 
find / -name myfile* | more

Cmd

Redirecting dir output to sort
 
dir /b log.* | sort
 
Reading sort input from file.txt
 
sort < file.txt

Redirecting cl.exe output to out.txt and errors to err.txt

cl.exe file.c >out.txt 2>err.txt

Append both output and errors to out.txt (mind the reversed sign)

cl.exe file.c >>out.txt 2<&1

Paging results

dir /b c:\my_large_dir | more
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This page was last modified on 2024-12-05 11:24:48