Bash Don Exit On Error
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Bash Don't Exit On Error
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Bash Exit On Error Code
is a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up Bash ignoring error for a particular command up vote 144 down vote favorite bash script exit on error 16 I am using following options set -o pipefail set -e In bash script to stop execution on error. I have 100 of script executing and I don't want to check return code of the script. But for a particular script I want to ignore the error. How can I do that ? linux bash share|improve this question asked Jun 27 '12 at 17:34 Vivek Goel 7,328955129 add a comment| bash set exit on error 3 Answers 3 active oldest votes up vote 238 down vote accepted The solution: particular_script || true Example: $ cat /tmp/1.sh particular_script() { false } set -e echo ein particular_script || true echo zwei particular_script echo drei $ bash /tmp/1.sh ein zwei drei will be never printed. Also, I want to add that when pipefail is on, it is enough for shell to think that the entire pipe has non-zero exit code when one of commands in the pipe has non-zero exit code (with pipefail off it must the last one). $ set -o pipefail $ false | true ; echo $? 1 $ set +o pipefail $ false | true ; echo $? 0 share|improve this answer edited Jun 27 '12 at 18:09 answered Jun 27 '12 at 17:37 Igor Chubin 25.5k65397 1 +1. As the Bash Reference Manual explains, "The shell does not exit" when the -e attribute is set "if the command that fails is part of the command list immediately following a while or until keyword, part of the test in an if statement, part of any command executed in a && or || list except the command following the final && or ||, any command in a pipeline but the last,
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Bash Exit Status Variable
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Bash Fail On Error
errors on Shell Script up vote 11 down vote favorite 6 I have a small snippet of a shell script which has the potential to throw many errors. I have the script currently set to globally stop on all errors. However i http://stackoverflow.com/questions/11231937/bash-ignoring-error-for-a-particular-command would like for this small sub-section is slightly different. Here is the snippet: recover database using backup controlfile until cancel || true; auto I'm expecting this to eventually throw a "file not found" error. However i would like to continue executing on this error. For any other error i would like the script to stop. What would be the best method of achieving this? Bash Version 3.00.16 bash shell unix share|improve this question edited Jul 24 '13 at 13:35 asked Jul 24 '13 at 9:38 http://stackoverflow.com/questions/17830326/ignoring-specific-errors-on-shell-script Stunt 1471212 2 Does this help? And, Welcome to SO! :) –S.R.I Jul 24 '13 at 9:42 That does help to improve my error reporting however it does not include anything for handling different errors in a different manor. I'm essentially trying to mimic the try{}catch{} from c# –Stunt Jul 24 '13 at 10:00 add a comment| 2 Answers 2 active oldest votes up vote 29 down vote accepted In order to prevent bash to ignore error for specific commands you can say: some-arbitrary-command || true This would make the script continue. For example, if you have the following script: $ cat foo set -e echo 1 some-arbitrary-command || true echo 2 Executing it would return: $ bash foo 1 z: line 3: some-arbitrary-command: command not found 2 In the absence of || true in the command line, it'd have produced: $ bash foo 1 z: line 3: some-arbitrary-command: command not found Quote from the manual: The shell does not exit if the command that fails is part of the command list immediately following a while or until keyword, part of the test in an if statement, part of any command executed in a && or || list except the command following the final && or ||, any command in a pipeline but the last, or if the command’s return status is being inverted with !. A trap on ERR, if set, is executed before the shell exits. EDIT: In order to change the behaviour such that in the execution
Start 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 http://serverfault.com/questions/153875/how-to-let-cp-command-dont-fire-an-error-when-source-file-does-not-exist hiring developers or posting ads with us Server Fault Questions Tags Users Badges Unanswered Ask Question http://www.davidpashley.com/articles/writing-robust-shell-scripts/ _ Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute: Sign up Here's how it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top How to let 'cp' command don't fire an error when source file does not exist? up vote on error 19 down vote favorite 4 I'm using Mac OS X. I'm trying to copying some files with cp command for a build script like this. cp ./src/*/*.h ./aaa But this command fires an error if there is no .h file in ./src directory. How to make the command don't fire the error? (silent failure) The error makes build result fail, but I just want to copy when only there are some header file. shell copy share|improve this question edited exit on error Nov 29 '14 at 20:16 Valentin Lorentz 1336 asked Jun 23 '10 at 2:55 Eonil 1,68482344 add a comment| 5 Answers 5 active oldest votes up vote 26 down vote accepted If you're talking about the error message, you can suppress that by sending it to the bit bucket: cp ./src/*/*.h ./aaa 2>/dev/null If you want to suppress the exit code and the error message: cp ./src/*/*.h ./aaa 2>/dev/null || : share|improve this answer answered Jun 23 '10 at 4:07 Dennis Williamson 41k866106 1 It would be nice to explain what : means in this context. –Piotr Dobrogost Feb 10 '14 at 15:35 7 @PiotrDobrogost: In Bash and some other shells the colon is a null utility (no-op). It's specified by POSIX. Since it always returns true, it's used here to suppress the exit code of a failed cp (should that be desired). The shell builtin true could be used instead and would be more readable. –Dennis Williamson Feb 10 '14 at 15:46 More about : – What Is the Purpose of the `:' (colon) GNU Bash Builtin? –Piotr Dobrogost Feb 10 '14 at 15:49 add a comment| up vote 6 down vote You're looking for something along the lines of if [ -e file ] then cp file /somewhere fi (Unfortunately, the -f option is not the droid you're looking for.) If you want to match a glob, that won't w
Bash Prompts About Writing Robust Bash Shell Scripts Many people hack together shell scripts quickly to do simple tasks, but these soon take on a life of their own. Unfortunately shell scripts are full of subtle effects which result in scripts failing in unusual ways. It's possible to write scripts which minimise these problems. In this article, I explain several techniques for writing robust bash scripts. Use set -u How often have you written a script that broke because a variable wasn't set? I know I have, many times. chroot=$1 ... rm -rf $chroot/usr/share/doc If you ran the script above and accidentally forgot to give a parameter, you would have just deleted all of your system documentation rather than making a smaller chroot. So what can you do about it? Fortunately bash provides you with set -u, which will exit your script if you try to use an uninitialised variable. You can also use the slightly more readable set -o nounset. david% bash /tmp/shrink-chroot.sh $chroot= david% bash -u /tmp/shrink-chroot.sh /tmp/shrink-chroot.sh: line 3: $1: unbound variable david% Use set -e Every script you write should include set -e at the top. This tells bash that it should exit the script if any statement returns a non-true return value. The benefit of using -e is that it prevents errors snowballing into serious issues when they could have been caught earlier. Again, for readability you may want to use set -o errexit. Using -e gives you error checking for free. If you forget to check something, bash will do it or you. Unfortunately it means you can't check $? as bash will never get to the checking code if it isn't zero. There are other constructs you could use: command if [ "$?"-ne 0]; then echo "command failed"; exit 1; fi could be replaced with command || { echo "command failed"; exit 1; } or if ! command; then