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Bash Script Fail On Error

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Script: #!/bin/bash touch /root/test 2> /dev/null if [ $? -eq 0 ] then echo "Successfully created file" exit 0 else echo "Could not create file" >&2 exit 1 fi With the Please enable JavaScript to view the comments powered by Disqus. Thanks for editing. –JRFerguson Oct 22 '13 at 13:36 add a comment| up vote 0 down vote Actually for your case I would say that the logic can be improved. How would family relationships change if legal system uses collective punishment? navigate here

The second use, ${1:-"Unknown Error"} means that if parameter 1 ($1) is undefined, substitute the string "Unknown Error" in its place. COMMAND_LAST # Will exit with status of last command. echo $? # Non-zero exit status returned -- command failed to execute. EXIT Exit - this is a pseudo-signal and is triggered when your script exits, either through reaching the end of the script, an exit command or by a command failing when

Bash Exit Script On Error

Is there a way to make a metal sword resistant to lava? Why? This is Bash's way of giving functions a "return value." [1]

Following the execution of a pipe, a $? gives the exit status of ls | bogus_command # bash: bogus_command: command not found echo $? # 0 # Note that the !

For example, when you create a directory, if the parent directory doesn't exist, mkdir will return an error. Especially if that script is used for the command line. 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 Stop Bash Script Running Execution: $ ./tmp.sh touch: cannot touch '/root/test': Permission denied $ echo $? 1 As you can see, since the last command run was touch the exit code reflects the true status

BTW, it doesn't abort the whole program in this case, too. Aborting." 1>&2 exit 1 fi Here we check to see if the cd command is successful. Within a script, an exit nnn command may be used to deliver an nnn exit status to the shell (nnn must I didn't know about the if [ -d $1 ] that's exactly what I needed.

For details and our forum data attribution, retention and privacy policy, see here Toggle navigation Benjamin Cane Home Archive RSS Twitter Mail Feed Understanding Exit Codes and how to use them Stop Bash Script Execution 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 Thanks for the help. Notice that we explicitly exit from the script at the end of trap command, otherwise the script will resume from the point that the signal was received.

  1. replace all local x=y with just x=y: # [CLEANUP=cleanup_cmd] run cmd [args...] # # `cmd` and `args...` A command to run and its arguments. # # `cleanup_cmd` A command that is
  2. Program defensively - expect the unexpected Your script should take into account of the unexpected, like files missing or directories not being created.
  3. Note that in cases like (false); …, the ERR trap is executed in the subshell, so it can't cause the parent to exit.
  4. Unfortunately shell scripts are full of subtle effects which result in scripts failing in unusual ways.
  5. 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:
  6. Related 5How to catch an error in a linux bash script?5Bash capture any error like -e but don't exit, do something else2How to have a bash script perform a specific action

Bash Script Fail On First Error

This becomes more important as your programs get more complex and you start having scripts launching other scripts, etc. Alternatively, or in addition, in bash (and ksh and zsh, but not plain sh), you can specify a command that's executed in case a command returns a nonzero status, with the Bash Exit Script On Error See my answer. Bash Script Fail If Any Command Fails Aborting." fi AND and OR lists Finally, we can further simplify our script by using the AND and OR control operators.

I only hope I clarified the set -e statement! http://onlinetvsoftware.net/bash-script/bash-script-tar-error.php add a comment| 1 Answer 1 active oldest votes up vote 237 down vote accepted Maybe you want set -e: http://www.davidpashley.com/articles/writing-robust-shell-scripts.html#id2382181 share|improve this answer answered Aug 13 '10 at 6:50 Alok The function name is directoryExists. –Patrick Oct 22 '13 at 13:57 add a comment| 5 Answers 5 active oldest votes up vote 4 down vote accepted Your script changes directories as This site is not affiliated with Linus Torvalds or The Open Group in any way. Stop Bash Script If Command Fails

Subtraction with a negative result I accepted a counter offer and regret it: can I go back and contact the previous company? The two lines change the working directory to the name contained in $some_directory and delete the files in that directory. If you look at exit codes in the context of scripts written to be used for the command line the answer is very simple. http://onlinetvsoftware.net/bash-script/bash-script-bus-error.php Using them, we can see how the $?

If you ask rm to delete a non-existent file, it will complain and your script will terminate. (You are using -e, right?) You can fix this by using -f, which will silently Stop Bash Script From Terminal david% touch "foo bar" david% find | xargs ls ls: ./foo: No such file or directory ls: bar: No such file or directory david% find -print0 | xargs -0 ls ./foo UNIX is a registered trademark of The Open Group.

trap 'err=$?; echo >&2 "Exiting on error $err"; exit $err' ERR.

EDIT: I think I found a workaround, although it probably isn't the best solution again: Code: #!/bin/bash set -e cmd1 cmd2 #exclude next command from causing script to terminate: set +e; if [ $filename = "foo" ]; will fail if $filename contains a space. Unexpected parent process id in output Password Protected Wifi, page without HTTPS - why the data is send in clear text? Shell Script Error Handling share|improve this answer edited Jul 8 '13 at 19:05 answered Jul 8 '13 at 18:48 gniourf_gniourf 1,291412 I meant the absence of such feature is a problem.

more stack exchange communities company blog Stack Exchange Inbox Reputation and Badges sign up log in tour help Tour Start here for a quick overview of the site Help Center Detailed There are several things you can do to prevent errors in these situations. Not the answer you're looking for? http://onlinetvsoftware.net/bash-script/bash-script-error-log.php It's common to use the (( keyword with the if keyword.

I have to say this doesn't feel very robust, but if it works for you, perhaps it is acceptable. Adv Reply December 11th, 2008 #8 jasper.davidson View Profile View Forum Posts Private Message 5 Cups of Ubuntu Join Date Jul 2008 Beans 26 Re: Make shell script exit as after every statement to catch syntax errors. (I expected such safe behavior from a sensible programming language... COMMAND_LAST # Will exit with status of last command.

$? reads the exit status of the last command

You then commented later that you only wanted to check for directory existence, not the ability to use cd, so answers don't need to use cd at all. Previous | Contents | Top | Next © 2000-2016, William E. Sample Script: #!/bin/bash touch /root/test echo created file The above sample script will execute both the touch command and the echo command. Exit status As you recall from previous lessons, every well-written program returns an exit status when it finishes.

On POSIX systems the standard convention is for the program to pass 0 for successful executions and 1 or higher for failed executions.