Home > Bash Script > Bash Script Terminate On Error

Bash Script Terminate On Error

Contents

Linux is a registered trademark of Linus Torvalds. 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 asked 11 months ago viewed 1002 times active 10 months ago Related 28How can I get bash to exit on backtick failure in a similar way to pipefail?2make `find` return with Note the inclusion # of the LINENO environment variable. http://sovidi.com/bash-script/bash-script-error-log.php

more hot questions question feed default about us tour help blog chat data legal privacy policy work here advertising info mobile contact us feedback Technology Life / Arts Culture / Recreation trap command signal [signal ...] There are many signals you can trap (you can get a list of them by running kill -l), but for cleaning up after problems there are only COMMAND_LAST # Will exit with status of last command.

$? reads the exit status of the last command This variable will print the exit code of the last run command.

Bash Script Exit With Error Message

After a function returns, $? gives the exit status of the last command executed in the function. If a program finishes successfully, the exit status will be zero. The return value is the exit status of the last command in list that is executed, or false if any of the expressions is invalid. [Emphasis added] share|improve this answer edited You can use command || true, or if you have a longer section of code, you can turn off the error checking, but I recommend you use this sparingly.

  1. 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
  2. The way to handle it is: function finish { # re-start service sudo service mongdb start } trap finish EXIT # Stop the mongod instance sudo service mongdb stop # (If
  3. In that case, the shell will interpret the variable as empty and the cd succeed, but it will change directories to the user's home directory, so beware!
  4. You can read more about parameter expansion in the bash man page under the topic "EXPANSIONS".
  5. inverts the exit status returned.
  6. 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.
  7. I recognize it's a bit more complicated, but it seems so useful.
  8. 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
  9. You're example script, as written, should exit after the first curl command failure the first time it calls false if errexit is set.
  10. Not the answer you're looking for?

I like to include the name of the program in the error message to make clear where the error is coming from. Your's should too. –RobertL Nov 6 '15 at 8:27 add a comment| up vote 1 down vote If you have errexit set, then the false statement should cause the script to Thanks. –kaizenCoder May 17 '15 at 9:58 7 yell: $0 is the path to the script. $* are all arguments. >&2 means “> redirect stdout to & pipe 2”. Exit Bash Script From Function It's possible to write scripts which minimise these problems.

You will probably discover your own situations where it will help make your bash scripts more reliable. Exit Bash Shell Script Let's rely on the EC2 command line tools: #!/bin/bash # define the base AMI ID somehow ami=$1 # Store the temporary instance ID here instance='' # While we are at it, asked 4 years ago viewed 42249 times active 1 month ago Related 20In a bash script, using the conditional “or” in an “if” statement0if env variable exists then exit out of Be prepared for spaces in filenames Someone will always use spaces in filenames or command line arguments and you should keep this in mind when writing shell scripts.

The script runs a curl command which sometimes fails to retrieve the intended file - however when this occurs the script doesn't error exit. Bash Script Exit While Loop You need to make sure that both the old and the new directories are moved to locations that are on the same partition so you can take advantage of the property A simple visual puzzle to die for what is the difference between \twocolumn and \documentclass[twocolumn]{book} Do COB LEDs usually need electrically insulating from the heatsink? To handle either case in the same script, you can use return 2> /dev/null || exit This will handle whichever invocation may be suitable.

Exit Bash Shell Script

Using if, we could write it this way: # A better way if cd $some_directory; then rm * else echo "Could not change directory! Related 2103Check if a directory exists in a shell script2882Can a Bash script tell which directory it is stored in?238Exit Shell Script Based on Process Exit Code721How do I prompt for Bash Script Exit With Error Message To do this make a copy of the data, make the changes in the copy, move the original out of the way and then move the copy back into place. Exit Bash Script Without Exiting Shell The basic code structure is like this: #!/bin/bash function finish { # Your cleanup code here } trap finish EXIT You place any code that you want to be certain to

If you forget to check something, bash will do it or you. http://sovidi.com/bash-script/bash-script-bus-error.php Browse other questions tagged bash shell-script or ask your own question. For more on set -e, see Greg's FAQ #105. –John1024 Nov 6 '15 at 7:55 @John1024 Thanks. For example, 1 == tests failed, 2 == compilation failed. Exit Bash Script If Command Fails

On Unix and Linux systems, programs can pass a value to their parent process while terminating. It will not exit after the first failed command in a loop. Why don't most major game engines use gifs for animated textures? this contact form Verbatim copying and distribution of this entire article is permitted in any medium, provided this copyright notice is preserved.

does not change the execution of the pipe. # Only the exit status changes. # =========================================================== # # Thanks, Stphane Chazelas and Kristopher Newsome.

echo normally exits with code=0, signally success.

Also the time where it is affected is reduced to the time between the two mvs, which should be very minimal, as the filesystem just has to change two entries in the Well-behaved UNIX commands, programs, and utilities return a 0 exit code upon successful completion, though there are some exceptions.

Likewise, functions within a script and the script How to map and sum a list fast? Bash Script Exit On Failure 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

Breaking a loop (even in normal operation) is considered bad practice. environment variable. $? Will the medium be able to last 100 years? navigate here rollback() { del_from_passwd $user if [ -e /home/$user ]; then rm -rf /home/$user fi exit } trap rollback INT TERM EXIT add_to_passwd $user cp -a /etc/skel /home/$user chown $user /home/$user -R

Create a new image from this now-modified instance. 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 If the exit code is anything other than 0 this indicates failure and the script will echo a failure message to stderr. Using exit codes in your bash scripts While removing the echo command from our sample script worked to provide an exit code, what happens when we want to perform one action

scratch=$(mktemp -d -t tmp.XXXXXXXXXX) # Insert dozens or hundreds of lines of code here... # All done, now remove the directory before we exit rm -rf "$scratch" What's wrong with this? special variable in bash. How rich can one single time travelling person actually become? In this case you'd want the user to not exist and all their files to be removed.

Only then does rm get executed; otherwise an error message is output and the program exits with a code of 1, indicating that an error has occurred. as part of a replica set, you # may instead need to do "sudo killall --wait /usr/bin/mongod".) Capping Expensive Resources There is another situation where the exit trap is very useful: errexit) - that it should terminate the script based on the "result" of exit 1. - so I have gone with exit but thanks for explanation –the_velour_fog Nov 6 '15 at so yell prefixes all arguments with the script name and prints to stderr.

Convince people not to share their password with trusted others Can a creature benefit from differently typed speed bonuses all named fast movement? Is 8:00 AM an unreasonable time to meet with my graduate students and post-doc?