https://www.jpsdomain.org/tags/posix/index.html Hugo en-us https://www.jpsdomain.org/windows/redirection/index.html Mon, 01 Jan 0001 00:00:00 +0000 https://www.jpsdomain.org/windows/redirection/index.html Originally written for and copyright by Information Security Magazine, February 2002 " Windows Security Scripting." Note: Under DOS & Win9x/ME some of the simple STDOUT redirection and pipes work, but none of the advanced STDERR or multiple command methods are supported. IO Redirection in Windows NT, 2000, XP, UNIX (sh, bash and variants) File Descriptors FD Description 1 STDOUT 2 STDERR 3+ Additional files as opened by the process Redirection Command Description cmd1 | cmd1 Pipe STDOUT of cmd1 into STDIN of cmd2 \> file Direct STDOUT to file, overwriting existing contents \>\> file Direct STDOUT to file, appending to existing contents `> file` 2\> file Direct STDERR to file, overwriting existing contents 2\>\> file Direct STDERR to file, appending to existing contents \< file Get STDIN from file 2\>&1 Direct STDERR to the same place as STDOUT \>& file Direct both STDOUT and STDERR to file 2\>& Duplicate STDOUT to STDERR echo 'foo' \>&2 Send output to STDERR instead of STDOUT Notes: Numbered file descriptions above may be used arbitrarily. noclobber is a UNIX setting that prevents overwriting (clobbering) existing files by redirection. UNIX /dev/null is equivalent to Windows NUL. Windows NUL is not case sensitive. ^ is the meta-character escape in DOS/Windows, so it may sometimes be necessary to use ^| (e.g. when using egrep in a batch file). You may use ^^ for a literal ^. Examples: Command Description dir c:\*.* > myls.txt Redirect output of ls into myls.txt, overwriting or creating myls.txt if necessary dir c:\winnt\*.* >> myls.txt Append more output of ls into myls.txt noisy_cmd > NUL Make STDOUT output from noisy_cmd go away noisy_cmd 2> NUL Make STDERR output from noisy_cmd go away noisy_cmd > NUL 2>&1 Make ALL output from noisy_cmd go away noisy_cmd 2> NUL 1>&2 Make ALL output from noisy_cmd go away noisy_cmd | more Pipe noisy_cmd STDOUT into more (or less or whatever) noisy_cmd 2>&1 | more Pipe noisy_cmd STDOUT and STDERR into more (this is great for those “net” commands that scroll off the screen when you try to get help) echo some message 1>&2 Use the echo command to send output to STDERR (it usually goes to STDOUT). Running Multiple Commands in Windows NT, 2000, UNIX (sh, bash and variants) Use parentheses to nest as needed.