Bash Standard Error Output
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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 Standard Error To Variable
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 To Stderr
'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 stderr and stdout to file 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
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 linux pipe standard error company Business Learn more about hiring developers or posting ads with us Stack Overflow redirect stderr to dev null Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 bash pipe stderr 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 158 down vote favorite 44 Hi I http://tldp.org/HOWTO/Bash-Prog-Intro-HOWTO-3.html am running a bash script that creates a log file for the execution of the command I use the following Command1 >> log_file 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 http://stackoverflow.com/questions/7526971/how-to-redirect-both-stdout-and-stderr-to-a-file 1,59621321 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 stderr to a file with Bash? –That1Guy May 5 at 15:19 add a comment| 5 Answers 5 active oldest votes up vote 229 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 135k20234273 72 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 117 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 20.3k43365 2 Not sure when this operator was added but it may not be available
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and http://stackoverflow.com/questions/2990414/echo-that-outputs-to-stderr policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with 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 standard error a minute: Sign up echo that outputs to stderr up vote 468 down vote favorite 81 Is there a standard Bash tool that acts like echo but outputs to stderr rather than stdout? I know I can do echo foo 1>&2 but it's kinda ugly and, I suspect, error prone (e.g. more likely to get edited wrong when things change). bash bash standard error share|improve this question edited Aug 19 '14 at 22:36 Steven Penny 1 asked Jun 7 '10 at 14:36 BCS 25.4k41145245 add a comment| 13 Answers 13 active oldest votes up vote 463 down vote accepted This question is old, but you could do this, which facilitates reading: >&2 echo "error" The operator '>&2' literally means redirect the address of file descriptor 1 (stdout) to the address of file descriptor 2 (stderr) for that command. depending on how deeply you want to understand it, read this: http://wiki.bash-hackers.org/howto/redirection_tutorial To avoid interaction with other redirections use subshell (>&2 echo "error") share|improve this answer edited Apr 8 at 7:25 Mateusz Konieczny 415319 answered May 8 '14 at 18:59 Marco Aurelio 4,8941913 80 alias errcho='>&2 echo' –BCS Aug 5 '14 at 21:29 3 @macmac, could you offer an explanation of this syntax or a link to more information? –allonhadaya Sep 25 '14 at 23:13 7 @allonhadaya, the operator '>&2' literally means redirect the address of file descriptor 1 (stdout) to the address of file descriptor 2 (stderr) for that command. depending on how deep