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Bash Exit Script On Error


Problem? I'm looking for a way to make it always abort on syntax errors. –imz -- Ivan Zakharyaschev Jul 8 '13 at 20:30 add a comment| up vote 0 down vote First, It behaves bad even without the arithmetic test! An advantage is that you now have a backup before you made your changes in case you need to revert. © 2013 Company Name FAQ Forum Quick Links Unanswered Posts http://waspsoft.com/bash-exit/bash-exit-on-error-script.html

About your wish: I expected such safe behavior from a sensible programming language... For details and our forum data attribution, retention and privacy policy, see here current community chat Unix & Linux Unix & Linux Meta your communities Sign up or log in to An idiom for the occasional command whose failure doesn't matter is command-that-may-fail || true. share|improve this answer answered May 20 '10 at 4:26 Matthew Flaschen 174k28368450 7 and you can add a newline after the && for readability –glenn jackman May 20 '10 at

Bash Exit Status Variable

Using if, we could write it this way: # A better way if cd $some_directory; then rm * else echo "Could not change directory! The second use, ${1:-"Unknown Error"} means that if parameter 1 ($1) is undefined, substitute the string "Unknown Error" in its place. Commands whose status is tested by a conditional (such as if, && or ||) do not terminate the script (otherwise the conditional would be pointless). Join them; it only takes a minute: Sign up Exit a Script On Error up vote 43 down vote favorite 7 I'm building a Shell Script that has a if function

  • echo 'Bad: has not aborted execution on syntax error!' Result (bash-3.2.39 or bash-3.2.51): $ ./sh-on-syntax-err ./sh-on-syntax-err: line 10: #: syntax error: operand expected (error token is "#") status 1 Bad: has
  • Every call I want to make is passed to this function so the entire script exits when a failure is hit.
  • In that case, the cd command will fail and the script executes the rm command on the current working directory.
  • You can also reset traps back to their default by using - as the command.   Signal Description INT Interrupt - This signal is sent when someone kills the script by pressing ctrl-c.
  • I would like to make my shell script so that if any of the commands in it return an error, the script immmediately exits without executing the rest of the commands.
  • An error exit function Since we will be checking for errors often in our programs, it makes sense to write a function that will display error messages.
  • asked 5 years ago viewed 51705 times active 10 months ago Linked 192 What does set -e mean in a bash script?
  • For example foo || bar will fail only if both foo and bar return non-zero value.

Improving the error exit function There are a number of improvements that we can make to the error_exit function. If you add a -p option then mkdir will create all the parent directories before creating the requested directory. trap : 0 echo >&2 ' ************ *** DONE *** ************ ' share|improve this answer answered Mar 6 '14 at 12:19 supercobra 2,90242737 1 trap 'abort' 0 <- why you Bash Exit Script Without Exiting Shell In particular you should use quotes around variables.

Also thanks to a_m0d for the info on traps (though not 100% relevant). –radman May 20 '10 at 5:07 add a comment| 7 Answers 7 active oldest votes up vote 440 Bash Exit On Non-zero ls | bogus_command # bash: bogus_command: command not found echo $? # 127 ! Meaning of Guns and ghee My home country claims I am a dual national of another country, the country in question does not. This doesn't let you write your own message, but often the failing command's own messages are enough.

Be atomic Sometimes you need to update a bunch of files in a directory at once, say you need to rewrite urls form one host to another on your website. Bash Exit Script Without Closing Shell For example, when you create a directory, if the parent directory doesn't exist, mkdir will return an error. pipe 1 would be stdout itself. If you only have a few cases where the failure of a command is not important, then I would toggle the "e" option as you have done.

Bash Exit On Non-zero

So -e is about the exit status of commands being non-zero, not about syntax errors in your script. Depending on the type of syntax error, the script might not even be executed at all. Bash Exit Status Variable A careful reading of the output of help set shows: -e Exit immediately if a command exits with a non-zero status. Bash Exit Script With Error Code Buy on Amazon Sponsored by Become a Sponsor Copyright © Benjamin Cane 2014 - Contact the Author

Not the answer you're looking for? http://waspsoft.com/bash-exit/bash-exit-at-error.html share|improve this answer edited Oct 24 '12 at 20:11 KitsuneYMG 9,31912647 answered Sep 4 '09 at 15:18 Shizzmo 8,50331314 2 With set -e You still can make some commands exit However, it seems silly to run the tests if compiling the code fails in the first place, in which case I'll just abort the tests. Publications Red Hat Enterprise Linux Troubleshooting Guide Identify, capture and resolve common issues faced by Red Hat Enterprise Linux administrators using best practices and advanced troubleshooting techniques What people are saying: Bash Exit Script If Command Fails

Train ride from Copenhagen to Malmo more hot questions question feed lang-sh about us tour help blog chat data legal privacy policy work here advertising info mobile contact us feedback Technology perhaps this must be reported as a bug/wish to bash developers The answer is definitely no! If the script is meant to be run by another script, you may want to define your own set of status code with particular meaning. navigate here The solution to this is to make the changes an (almost) atomic operation.

What is the sh -c command? Bash Exit Script From Subshell Within the parenthesis the commands are chained together using the && and || constructs again. Why is this important?

Hot Network Questions The Woz Monitor My home country claims I am a dual national of another country, the country in question does not.

Using Map to convert Feet + Inches to Inches in a List of Lists Can I use an HSA as investment vehicle by overcontributing temporarily? Removing if: #!/bin/bash set -e # exit on any error readonly a=(1 2) # A syntax error is here: (( "${a[#]}" == 2 )) echo status $? Exiting..." >&2 exit 1 } trap 'abort' 0 set -e # Add your script below.... # If an error occurs, the abort() function will be called. #---------------------------------------------------------- # ===> Your script Bash Exit Script From Function That does make it easier.

The 1 is a return code, so you can change it if you want, say, 1 to mean a successful run and -1 to mean a failure or something like that. In general, it is considered bad practice to use set -e, because all errors (i.e., all non-zero returns from commands) should be smartly handled by the script (think robust script, not share|improve this answer edited Aug 11 at 8:09 Édouard Lopez 8,72464469 answered Aug 26 '14 at 21:24 c.gutierrez 1,528910 3 I'm fairly new to unix scripting. http://waspsoft.com/bash-exit/bash-exit-on-any-error.html Using them, we can see how the $?

I once had a Unix system administrator who wrote a script for a production system containing the following 2 lines of code: # Example of a really bad idea cd $some_directory david% foo() { for i in $@; do printf "%s\n" "$i"; done }; foo bar "baz quux" bar baz quux david% foo() { for i in "$@"; do printf "%s\n" "$i"; So to check the exit status, we could write the script this way: # Check the exit status cd $some_directory if [ "$?" = "0" ]; then rm * else echo environment variable contains the exit status of the previous program.

share|improve this answer answered Dec 7 '10 at 22:12 Gilles 55.6k15118178 According to mywiki.wooledge.org/BashFAQ/105 - this feature has a history of being obscure and convoluted in its determination of You can get this # value from the first item on the command line ($0). up vote 234 down vote favorite 49 I'm writing a script in Bash to test some code. That usage is simply a style thing.

On POSIX systems the standard convention is for the program to pass 0 for successful executions and 1 or higher for failed executions. Explanation (based on flying sheep comment). The list constructs use exit codes to understand whether a command has successfully executed or not. On Unix and Linux systems, programs can pass a value to their parent process while terminating.

so you want: if [ ${#a[*]} -eq 2 ]; then share|improve this answer edited Jul 8 '13 at 19:16 Evan Teitelman 13.1k43758 answered Jul 8 '13 at 17:18 higuita 47237 Tango Icons Tango Desktop Project. Using "set -e" as accepted above works fine. –pauldoo Sep 2 '15 at 19:45 add a comment| up vote 1 down vote In case script is calling subscript inside, the pipefail By not defining proper exit codes you could be falsely reporting successful executions which can cause issues depending on what the script does.

It would be nice if you could fix these problems, either by deleting the lock files or by rolling back to a known good state when your script suffers a problem. Or, without set -e: bash -n "$0" || exit –Daniel S Aug 27 '15 at 9:56 add a comment| up vote 4 down vote You are probably mislead about the genuine Note: is supposed to be just a number. We can use something similar to: if ( set -o noclobber; echo "$$" > "$lockfile") 2> /dev/null; then trap 'rm -f "$lockfile"; exit $?' INT TERM EXIT critical-section rm -f "$lockfile"

And given that I'm no bash expert, it leads me to believe that my logic is faulty, and there's something wrong with this methodology, otherwise, I feel others would have given die does the same as yell, but exits with a non-0 exit status, which means “fail”. Skeletal formula for carbon with two double bonds Password Protected Wifi, page without HTTPS - why the data is send in clear text? Anywhere else should abort the script. –jordanm Jul 8 '13 at 16:09 @jordanm Ok, this can be an explanation why set -e hasn't worked.