Error Output Redirect
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is connected to the terminal keyboard and standard output and error to the terminal screen. The way of indicating an end-of-file on the redirect error output dos default standard input, a terminal, is usually
Redirect Error Output To File
output redirection is: % command -[options] [arguments] < input file > output file If you are using csh and do not have the noclobber variable set, using > and >& to redirect output will overwrite any existing file of that name. Setting noclobber prevents this. Using >! and >&! always forces the file to be overwritten. Use >> and >>& to append output to existing files. Redirection may fail under some circumstances: 1) if you have the variable noclobber set and you attempt to redirect output to an existing file without forcing an overwrite, 2) if you redirect output to a file you don't have write access to, and 3) if you redirect output to a directory. Examples: % who > names Redirect standard output to a file named names % (pwd; ls -l) > out Redirect output of both commands to a file named out % pwd; ls -l > out Redirect output of ls command only to a file named out Input redirection can be useful, for example, if you ha
>20.3. Applications
Redirect Error Output Unix
stderr (error messages output to the screen). These, and any redirect error output to dev null other open files, can be redirected. Redirection simply means capturing output from a file, command, program, script, or redirect error output tcsh even code block within a script (see Example 3-1 and Example 3-2) and sending it as input to another file, command, program, or script.
Each http://sc.tamu.edu/help/general/unix/redirection.html open file gets assigned a file descriptor. [2] The file descriptors for stdin, stdout, and stderr are 0, 1, and 2, respectively. For opening additional files, there remain descriptors 3 to 9. It is sometimes useful to assign one of these additional file descriptors to stdin, stdout, or stderr as http://www.tldp.org/LDP/abs/html/io-redirection.html a temporary duplicate link. [3] This simplifies restoration to normal after complex redirection and reshuffling (see Example 20-1). COMMAND_OUTPUT > # Redirect stdout to a file. # Creates the file if not present, otherwise overwrites it. ls -lR > dir-tree.list # Creates a file containing a listing of the directory tree. : > filename # The > truncates file "filename" to zero length. # If file not present, creates zero-length file (same effect as 'touch'). # The : serves as a dummy placeholder, producing no output. > filename # The > truncates file "filename" to zero length. # If file not present, creates zero-length file (same effect as 'touch'). # (Same result as ": >", above, but this does not work with some shells.) COMMAND_OUTPUT >> # Redirect stdout to a file. # Creates the file if not present, otherwise appends to it. # Single-line redirection commands (affect only the line they are on): # -------------------------------------------------------------------- 1>filename # Redirect stdout to file "filename." 1>>filename #here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us http://stackoverflow.com/questions/1420965/redirect-stdout-and-stderr-to-a-single-file Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community https://www.tutorialspoint.com/unix/unix-io-redirections.htm Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up Redirect stdout and stderr to a single file up vote 361 down vote favorite 97 I'm trying to redirect all output (stdout + stderr) of a DOS command to a single file: C:\>dir 1> a.txt 2> a.txt The process cannot access the file because error output it is being used by another process. Is it possible, or should I just redirect to two separate files? windows command-line cmd pipe share|improve this question edited Oct 9 '15 at 19:39 Peter Mortensen 10.2k1369107 asked Sep 14 '09 at 11:20 ripper234 66.6k167464747 2 TechNet: Using command redirection operators (answers this better than any of the answers here). –Martin Prikryl May 11 at 6:09 add a comment| 6 Answers 6 active oldest votes up vote 556 down vote accepted You want: dir > a.txt redirect error output 2>&1 share|improve this answer answered Sep 14 '09 at 11:23 Anders Lindahl 24.7k55275 10 thanks for this, didn't know that this unix shell syntax works for DOS too! –chaindriver Aug 14 '12 at 17:00 11 this is great for hiding all output.. net stop w3svc >NUL 2>&1.. thanks! –wasatchwizard Apr 4 '13 at 17:55 1 @wasatchwizard Ithink I had trouble with that, but >NUL 2>NUL worked fine –FrinkTheBrave Aug 4 '14 at 8:24 4 If there is a Handle, there cannot be a space between the Handle (i.e. 2) and the redirect operator (i.e. >). Therefore 2> 2.txt works (or 2> &1) 2 > 2.txt does not; 2 > &1 does not. –The Red Pea Apr 3 '15 at 21:41 Reference document from Microsoft: support.microsoft.com/en-us/kb/110930 –Jonathan Benn Feb 3 at 18:58 | show 1 more comment up vote 101 down vote Anders Lindahl's answer is correct, but it should be noted that if you are redirecting stdout to a file and want to redirect stderr as well then you MUST ensure that 2>&1 is specified AFTER the 1> redirect, otherwise it will not work. REM *** WARNING: THIS WILL NOT REDIRECT STDERR TO STDOUT **** dir 2>&1 > a.txt share|improve this answer edited Oct 9 '15 at 19:40 Peter Mortensen 10.2k1369107 answered May 23 '13 at 11:59 DelboyJay 1,1791511 2 AFTER is what cost me hours to figure out what's wrong DelboyJay! Thank you! –Nam G VU Dec 20 '13 at 7:10 Is it ex
- Directories Unix - File Permission Unix - Environment Unix - Basic Utilities Unix - Pipes & Filters Unix - Processes Unix - Communication Unix - The vi Editor Unix Shell Programming Unix - What is Shell? Unix - Using Variables Unix - Special Variables Unix - Using Arrays Unix - Basic Operators Unix - Decision Making Unix - Shell Loops Unix - Loop Control Unix - Shell Substitutions Unix - Quoting Mechanisms Unix - IO Redirections Unix - Shell Functions Unix - Manpage Help Advanced Unix Unix - Regular Expressions Unix - File System Basics Unix - User Administration Unix - System Performance Unix - System Logging Unix - Signals and Traps Unix Useful Resources Unix - Useful Commands Unix - Quick Guide Unix - Builtin Functions Unix - System Calls Unix - Commands List Unix - Useful Resources Unix - Discussion Selected Reading Developer's Best Practices Questions and Answers Effective Resume Writing HR Interview Questions Computer Glossary Who is Who Unix - Shell Input/Output Redirections Advertisements Previous Page Next Page Most Unix system commands take input from your terminal and send the resulting output back to your terminal. A command normally reads its input from a place called standard input, which happens to be your terminal by default. Similarly, a command normally writes its output to standard output, which is also your terminal by default. Output Redirection The output from a command normally intended for standard output can be easily diverted to a file instead. This capability is known as output redirection: If the notation > file is appended to any command that normally writes its output to standard output, the output of that command will be written to file instead of your terminal − Check following who command which would redirect complete output of the command in users file. $ who > users Notice that