Error Output Redirection Bash
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a stderr redirect stderr to a stdout redirect stderr and stdout to a file redirect stderr and stdout to stdout redirect stderr and stdout to stderr 1 'represents' stdout and 2 stderr.
Bash Redirect Error Output To File
A little note for seeing this things: with the less command you can view bash redirect error output to /dev/null both stdout (which will remain on the buffer) and the stderr that will be printed on the screen, but erased as bash script redirect error output you try to 'browse' the buffer. 3.2 Sample: stdout 2 file This will cause the ouput of a program to be written to a file.
ls -l > ls-l.txtHere, a file called
Bash Output Redirection Not Working
'ls-l.txt' will be created and it will contain what you would see on the screen if you type the command 'ls -l' and execute it. 3.3 Sample: stderr 2 file This will cause the stderr ouput of a program to be written to a file.
grep da * 2> grep-errors.txtHere, a file called 'grep-errors.txt' will be created and it will contain what you would see the
Bash Output Redirection 2 &1
stderr portion of the output of the 'grep da *' command. 3.4 Sample: stdout 2 stderr This will cause the stderr ouput of a program to be written to the same filedescriptor than stdout.
grep da * 1>&2Here, the stdout portion of the command is sent to stderr, you may notice that in differen ways. 3.5 Sample: stderr 2 stdout This will cause the stderr ouput of a program to be written to the same filedescriptor than stdout.
grep * 2>&1Here, the stderr portion of the command is sent to stdout, if you pipe to less, you'll see that lines that normally 'dissapear' (as they are written to stderr) are being kept now (because they're on stdout). 3.6 Sample: stderr and stdout 2 file This will place every output of a program to a file. This is suitable sometimes for cron entries, if you want a command to pass in absolute silence.
rm -f $(find / -name core) &> /dev/nullThis (thinking on the cron entry) will delete every file called 'core' in any directory. Notice that you should be pretty sure of what a command is doing if you are going to wipe it's output. Next Previous Contents
12, 2008 in BASH Shell, Linux, UNIXQ. How do I redirect stderr to stdout? How do I redirect stderr to a file? A. Bash and other modern shell provides bash redirect append I/O redirection facility. There are 3 default standard files (standard streams) open: [a]
Unix Redirect All Output To File
stdin - Use to get input (keyboard) i.e. data going into a program.
[b] stdout - Use to write information bash error to stdout (screen)[c] stderr - Use to write error message (screen)Understanding I/O streams numbersThe Unix / Linux standard I/O streams with numbers:HandleNameDescription0 stdin Standard input1 stdout Standard output2 stderr Standard errorRedirecting the standard error stream http://tldp.org/HOWTO/Bash-Prog-Intro-HOWTO-3.html to a fileThe following will redirect program error message to a file called error.log: $ program-name 2> error.log$ command1 2> error.logRedirecting the standard error (stderr) and stdout to fileUse the following syntax: $ command-name &>file OR $ command > file-name 2>&1 Another useful example: # find /usr/home -name .profile 2>&1 | moreRedirect stderr to stdoutUse the command as follows: $ command-name 2>&1 Share http://www.cyberciti.biz/faq/redirecting-stderr-to-stdout/ this tutorial on:TwitterFacebookGoogle+Download PDF version Found an error/typo on this page?About the author: Vivek Gite is a seasoned sysadmin and a trainer for the Linux/Unix & shell scripting. Follow him on Twitter. OR read more like this:How do I save or redirect stdout and stderr into different files?Linux Redirect Error Output To FileBASH Shell Redirect Output and Errors To /dev/nullUnix and Linux: Redirect Error Output To null CommandPrinting output of c program to a file in LinuxUnix / Linux: Save Output To FilePython Run External Command And Get Output On Screen or In VariablePython Execute Unix / Linux Command ExamplesLinux / Unix Find Command: Avoid Permission Denied MessagesHow to gzip and keep original file on Unix or Linux command line{ 11 comments… add one } Sayed Ahmad February 12, 2012, 12:11 amWhat this mean? $ command > file-name 2>&1 Reply Link Hesham M January 22, 2014, 3:34 pmThis means redirect stdout to file-name, with that in mind redirect stderr t stdout. This will lead to both stderr and stdout go to file-name. Reply Link Shane Hathaway February 24, 2012, 1:02 amSayed: that line means execute the command while redirecting both stdout and stderr to a
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 http://stackoverflow.com/questions/7526971/how-to-redirect-both-stdout-and-stderr-to-a-file us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community 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 How to redirect both stdout and stderr to a file up vote 162 down vote favorite 45 Hi I am running a bash script that creates a log file for the execution of the command I use the following Command1 >> log_file error output Command2 >> log_file This only sends the standard output and not the standard error which appears on the terminal. Can I log both the stderr and stdout logged to a file? bash stdout stderr share|improve this question edited Sep 23 '11 at 10:11 asked Sep 23 '11 at 9:35 sdmythos_gr 1,64621321 2 possible duplicate of Redirect stderr and stdout in a bash script –Nathan Aug 19 '14 at 19:35 Possible duplicate of How can I redirect and append both stdout and redirect error output stderr to a file with Bash? –That1Guy May 5 at 15:19 add a comment| 5 Answers 5 active oldest votes up vote 235 down vote accepted If you want to log to the same file: command1 >> log_file 2>&1 If you want different files: command1 >> log_file 2>> err_file share|improve this answer answered Sep 23 '11 at 9:37 Mat 135k21234273 73 And just to save someone else the frustration, note that the order is important: 2>&1 needs to occur after >> log_file. –Rufflewind Jan 2 '14 at 6:34 2 Why >> and not > ? –user3527975 Mar 16 at 21:38 3 >> appends to the file, > overwrites. Search for "shell redirection" for more details. –Mat Mar 17 at 5:04 add a comment| up vote 119 down vote The simplest syntax to redirect both is: command &> logfile If you want to append to the file instead of overwrite: command &>> logfile share|improve this answer answered Sep 23 '11 at 10:14 Costi Ciudatu 20.5k43366 2 Not sure when this operator was added but it may not be available in older versions of Bash. It does appear to be working on my machine which runs Gnu bash v3.2.48. –James Wald Apr 10 '14 at 7:32 5 @CostiCiudatu the &>> operator does not seem to work in Mac OS X; safer to use Mat's solution imo. –James Fennell May 24 '14 at 18:28 4 @JamesFennell You're right, I wasn't aware of that. I upvoted the accepted an