Home > Bash Script > Bash Script Error Handling

Bash Script Error Handling

Contents

Thus, transferring this idea to the original use case, a solution could look like this: $ cat test.sh set -e trap "rm -f run_script.lck" ERR if [ -f run_script.lck ]; then This database contains tables for the message, the corresponding stack trace and the important environment variables. no crash happens, e.g. Access the shell on Mac via the Terminal.app Unlike more recently designed languages, shell script does not have an easy answer for error handling. http://onlinetvsoftware.net/bash-script/bash-script-bus-error.php

is_shell_attribute_set e; then set -e e_was_set=0 fi "$cmd" "[email protected]" & wait $! || { exit_code=$? } if [ "$e_was_set" = 0 ] && is_shell_attribute_set e; then set +e fi if [ Fortunately bash provides a way to run a command or function when it receives a unix signal using the trap command. At a minimum, the gotchas in question should be well-understood. –Charles Duffy Sep 11 '12 at 13:17 2 set -e -o pipefail -u # and know what you are doing Browse other questions tagged bash shell shell-script error-handling or ask your own question.

Bash Throw Error

function directoryExists { # was: do the cd in a sub-shell so it doesn't change our own PWD # was: if errmsg=$( cd -- "$1" 2>&1 ) ; then if [ 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 No, create an account now. To read more or take a look at the source, see GitHub: https://github.com/niieani/bash-oo-framework#error-handling-with-exceptions-and-throw share|improve this answer edited May 3 '15 at 22:19 community wiki 3 revsniieani add a comment| up vote

Broken code get noticed because functioning code is the primary concern. –Draemon Jul 11 '14 at 18:54 @Draemon, the function keyword is bad practice, introducing gratuitous incompatibility with POSIX 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 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 Bash Script Error Output Since cd returns a non-zero status on failure, you could do: cd -- "$1" && echo OK || echo NOT_OK You could simply exit on failure: cd -- "$1" || exit

Use set -u How often have you written a script that broke because a variable wasn't set? I think this should have been the default behavior: since such errors almost always signify something unexpected, it is not really 'sane' to keep executing the following commands. It will immediately stop your script if a simple command fails. The error from cp does not matter unless we explicitly make it matter by passing it to our script's caller.

For example $ cat test.sh set -e trap "echo foo" ERR if [ $# == 1 ]; then exit 0 fi false $ bash test.sh foo $ bash test.sh 1 $ Bash Script Error Log Does mean=mode imply a symmetric distribution? Why does Windows show "This device can perform faster" notification if I connect it clumsily? You can get this # value from the first item on the command line ($0). # Reference: This was copied from PROGNAME=$(basename $0) function error_exit { # ---------------------------------------------------------------- # Function

Bash Script Error Checking

is_shell_attribute_set e; then set -e e_was_set=0 fi "$cmd" "[email protected]" & wait $! || { exit_code=$? } if [ "$e_was_set" = 0 ] && is_shell_attribute_set e; then set +e fi if [ I usually just copy-and-paste the code below into my scripts. Bash Throw Error if failing_command, failing_command || fallback). Bash Script Error Handling Trap Does mean=mode imply a symmetric distribution?

Limit involving exponentials and arctangent without L'Hôpital more hot questions question feed lang-bsh about us tour help blog chat data legal privacy policy work here advertising info mobile contact us feedback check over here Now I have all the information I want to log. TRAP ERR ! ! ! ###~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~## # # FUNCTION: BACKTRACE # ###~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~## function backtrace { local _start_from_=0 local params=( "[email protected]" ) if (( "${#params[@]}" >= "1" )) then _start_from_="$1" fi local What are the canonical white spaces? Bash Script Error Command Not Found

Convince people not to share their password with trusted others What are the canonical white spaces? shopt -s expand_aliases alias die='error_exit "Error ${0}(@`echo $(( $LINENO - 1 ))`):"' I usually put a call to the cleanup function in side the error_exit function, but this varies from script 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 his comment is here bash error-handling error-logging share|improve this question asked Sep 15 '08 at 17:09 community wiki Noob add a comment| 14 Answers 14 active oldest votes up vote 92 down vote Use a

After logging the error, I will still write the contents of that file to STDERR, so the user is not left in the dark with scripts that do run interactively. Bash Script Error Message local ARRAY=( `caller 0` ) Error_Create_Init_File # Write the error message (from STDERR) and read the generated autonumber: local INSERT_ID=`$SQLITE3_EXECUTABLE -batch -init $ERROR_INIT_SQLITE $ERRORDB "INSERT INTO ErrorLog(strMessage) VALUES(CAST(x'$(Error_Hexit_File $ERROROUTPUT)' AS TEXT));SELECT It is very important to check the exit status of programs you call in your scripts.

You can read more about parameter expansion in the bash man page under the topic "EXPANSIONS".

david% bash /tmp/shrink-chroot.sh $chroot= david% bash -u /tmp/shrink-chroot.sh /tmp/shrink-chroot.sh: line 3: $1: unbound variable david% Use set -e Every script you write should include set -e at the top. Another benefit might be full POSIX compatibility, though it is not so important as ERR pseudo-signal is supported in all major shells. more stack exchange communities company blog Stack Exchange Inbox Reputation and Badges sign up log in tour help Tour Start here for a quick overview of the site Help Center Detailed Bash Script Error Exit echo "Example of error with line number and message" error_exit "$LINENO: An error has occurred." Do you have a better error handling routine that you use in BASH scripts?

When you select something to buy, you find yourself presented with similar items as kind suggestions. That usage is simply a style thing. 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. weblink There are several things you can do to prevent errors in these situations.

To write such scripts can be quite painful, as all errors occur out of sight as well. This script does one thing; it copies a single file from one volume to another using the cp program. The exit status is not visible on the command line. Using -e gives you error checking for free.

Relying in /bin/sh being anything but a Bourne shell is bad style and will likely break sooner or later. 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. The run_script.lck file will be deleted in the end of the program.