Linux Bash Script Stop On Error
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x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 6.2 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up bash errexit Automatic exit from bash shell script on error up vote 283 down vote favorite 49 I've been writing some shell script and I would find it useful if there was the ability to halt the execution of said shell script if any of the commands failed. See below for an example: #!/bin/bash cd some_dir ./configure --some-flags make make install So in this case if bash set +e the script can't change to the indicated directory then it would certainly not want to do a ./configure afterwards if it fails. Now I'm well aware that I could have an if check for each command (which I think is a hopeless solution), but is there a global setting to make the script exit if one of the commands fails? bash shell exit share|improve this question edited Mar 29 '15 at 23:26 asked May 20 '10 at 4:21 radman 5,67462242 I did have a quick look for duplicates and couldn't find any. –radman May 20 '10 at 4:22 1 answer goes to Adam for the detail regarding set -e (which is exactly wanted). 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 451 down vote accepted Use the set -e builtin: #!/bin/bash set -e # Any subsequent(*) commands which fail will cause the shell script to exit immediately Alternatively, you can pass -e on the command line: bash -e my_script.sh You can also disable
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Bash Disable Exit On Error
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Bash Set O
programmers, just like you, helping each other. Join them; it only takes a minute: Sign up Aborting a shell script if any command returns a non-zero value? up vote 241 down vote favorite 71 I have a http://stackoverflow.com/questions/2870992/automatic-exit-from-bash-shell-script-on-error Bash shell script that invokes a number of commands. I would like to have the shell script automatically exit with a return value of 1 if any of the commands return a non-zero value. Is this possible without explicitly checking the result of each command? e.g. dosomething1 if [[ $? -ne 0 ]]; then exit 1 fi dosomething2 if [[ $? -ne 0 ]]; then exit 1 fi linux bash unix shell share|improve http://stackoverflow.com/questions/821396/aborting-a-shell-script-if-any-command-returns-a-non-zero-value this question edited Sep 16 '12 at 11:01 Mat 136k21235274 asked May 4 '09 at 18:55 Jin Kim 4,690113560 3 In addition to set -e, also do set -u (or set -eu). -u puts an end to the idiotic, bug-hiding behavior that you can access any nonexistent variable and have a blank value produced with no diagnostics. –Kaz Feb 21 '14 at 1:36 add a comment| 8 Answers 8 active oldest votes up vote 419 down vote accepted Add this to the beginning of the script: set -e This will cause the shell to exit immediately if a simple command exits with a nonzero exit value. A simple command is any command not part of an if, while, or until test, or part of an && or || list. See the bash(1) man page on the "set" internal command for more details. I personally start almost all shell scripts with "set -e". It's really annoying to have a script stubbornly continue when something fails in the middle and breaks assumptions for the rest of the script. share|improve this answer edited May 4 '09 at 19:16 answered May 4 '09 at 19:00 Ville Laurikari 17k54449 30 That would work, but I like to use "#!/usr/bin/env bash" because I frequently run bash from somewhere other than /bin. And "#!/usr/bi
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 http://unix.stackexchange.com/questions/82224/how-to-make-bash-abort-the-execution-of-a-script-on-syntax-error Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Unix & Linux Questions Tags Users Badges Unanswered Ask Question _ Unix & Linux Stack Exchange is http://bencane.com/2014/09/02/understanding-exit-codes-and-how-to-use-them-in-bash-scripts/ a question and answer site for users of Linux, FreeBSD and other Un*x-like operating systems. Join them; it only takes a minute: Sign up Here's how it works: Anybody can ask a question Anybody can on error answer The best answers are voted up and rise to the top How to make bash abort the execution of a script on syntax error? up vote 14 down vote favorite 5 To be on safe side, I'd like bash abort the execution of a script if it encounters a syntax error. To my surprise, I can't achieve this. (set -e is not enough.) Example: #!/bin/bash # Do exit exit on error on any error: set -e readonly a=(1 2) # A syntax error is here: if (( "${a[#]}" == 2 )); then echo ok else echo not ok fi echo status $? 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 not aborted execution on syntax error! $ Well, we can't check $? after every statement to catch syntax errors. (I expected such safe behavior from a sensible programming language... perhaps this must be reported as a bug/wish to bash developers) More experiments if makes no difference. Removing if: #!/bin/bash set -e # exit on any error readonly a=(1 2) # A syntax error is here: (( "${a[#]}" == 2 )) echo status $? echo 'Bad: has not aborted execution on syntax error!' Result: $ ./sh-on-syntax-err ./sh-on-syntax-err: line 6: #: syntax error: operand expected (error token is "#") status 1 Bad: has not aborted execution on syntax error! $ Perhaps, it's related to exercise 2 from http://mywiki.wooledge.org/BashFAQ/105 and has something to do with (( )). But I find it still unreasonable to continue executing afte a syntax error. No, (( )) makes no difference! It b
exit codes, exit codes are important and this article describes how to use them in your scripts and understand them in general. Written by Benjamin Cane on 2014-09-02 14:45:00| 4 min read Sponsored by Lately I've been working on a lot of automation and monitoring projects, a big part of these projects are taking existing scripts and modifying them to be useful for automation and monitoring tools. One thing I have noticed is sometimes scripts use exit codes and sometimes they don't. It seems like exit codes are easy for poeple to forget, but they are an incredibly important part of any script. Especially if that script is used for the command line. What are exit codes? On Unix and Linux systems, programs can pass a value to their parent process while terminating. This value is referred to as an exit code or exit status. On POSIX systems the standard convention is for the program to pass 0 for successful executions and 1 or higher for failed executions. Why is this important? If you look at exit codes in the context of scripts written to be used for the command line the answer is very simple. Any script that is useful in some fashion will inevitably be either used in another script, or wrapped with a bash one liner. This becomes especially true if the script is used with automation tools like SaltStack or monitoring tools like Nagios, these programs will execute scripts and check the status code to determine whether that script was successful or not. On top of those reasons, exit codes exist within your scripts even if you don't define them. By not defining proper exit codes you could be falsely reporting successful executions which can cause issues depending on what the script does. What happens if I don't specify an exit code In Linux any script run from the command line has an exit code. With Bash scripts, if the exit code is not specified in the script itself the exit code used will be the exit code of the last command run. To help explain exit codes a little better we are going to use a quick sample script. Sample Script: #!/bin/bash touch /root/test echo created file The above sample script will execute both the touch command and the echo command. When we execute this script (as a non-root user) the touch command will fail, ideally since the touch command failed we would want the exit code of the script to indicate failure with an appropriate exit code. To check the exit code we can simply print the $? special variable in bash. This variable will print the exit code of the last run command. Execution: $ ./tmp.sh tou