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Bash Script Exit On Command Error


It's common to use the (( keyword with the if keyword. But what happens if the directory named in $some_directory doesn't exist? 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 My question is not about set -e, it's about the unsafety of bash if it can't be made to abort on sytax errors. http://onlinetvsoftware.net/bash-script/bash-script-error-exit.php

In practice, all shells ignore failures of the elements of the pipeline other than the last one, and exhibit one of two behaviors regarding the last pipeline element: ATT ksh and command fails but error doesn't bubble up), local variable declaration: local myvar=$(subcommand) will always return 0! 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. If scripts do not properly use exit codes, any user of those scripts who use more advanced commands such as list constructs will get unexpected results on failures.

Bash Script Exit If Command Fails

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 UNIX is a registered trademark of The Open Group. true echo "exit status of \"! The lockfile will be left there and your script won't run again until it's been deleted.

About your wish: I expected such safe behavior from a sensible programming language... The return code of the echo (or other command that ran with the backtick output) will replace the 0 return code. special variable to print the exit code of the script. Bash Shell Script Exit Did Donald Trump call Alicia Machado "Miss Piggy" and "Miss Housekeeping"?

In a pipe it would have failed, but here the error isn't caught. fi return $exit_code } is_shell_attribute_set() { # attribute, like "x" case "$-" in *"$1"*) return 0 ;; *) return 1 ;; esac } Example of usage: #!/bin/sh set -e # Source Script: #!/bin/bash touch /root/test If we remove the echo command from the script we should see the exit code of the touch command. Why did companions have such high social standing?

How rich can one single time travelling person actually become? Bash Script Exit While Loop 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 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 The disadvantage of this technique is that you need to use twice as much disk space and that any process that keeps files open for a long time will still have

  1. I didn't want to focus on set -e -- it's just a bit close to my goals, that's why it is mentioned and used here.
  2. environment variable. $?
  3. No, (( )) makes no difference!
  4. I only hope I clarified the set -e statement!
  5. There are several things you can do to prevent errors in these situations.
  6. The solution is to declare the variable first: function testcase() { local MYRESULT MYRESULT=$(false) if (( $? != 0 )); then echo "False returned false!" return 1 fi return 0 }

Bash Script Command Exit Code

Is there a better way I hope? Modern soldiers carry axes instead of combat knives. Bash Script Exit If Command Fails So - is there a way to get bash to treat a non-zero returncode inside a backtick as reason enough to exit? Bash Script Exit With Error Message up vote 5 down vote favorite 1 I made the following script: # !/bin/bash # OUTPUT-COLORING red='\e[0;31m' green='\e[0;32m' NC='\e[0m' # No Color # FUNCTIONS # directoryExists - Does the directory exist?

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 http://onlinetvsoftware.net/bash-script/bash-script-error-command-not-found.php Hot Network Questions Which requires more energy: walking 1 km or cycling 1 km at the same speed? on a true command. Since this status is ignored, it does not cause the parent shell to exit. Bash Script Exit On Failure

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 Using -e gives you error checking for free. So, thank you a lot! (I'm used to proram Java, and checking for a directory in an if statement is not exactly common in Java) –Thomas De Wilde Oct 22 '13 his comment is here While this is useful in many cases such as (cd /some/dir && somecommand) where the parentheses are used to keep an operation such as a current directory change local, it violates

Script: #!/bin/bash touch /root/test 2> /dev/null if [ $? -eq 0 ] then echo "Successfully created file" else echo "Could not create file" >&2 fi In the above revision of our Bash Script Exit Function Any script that is useful in some fashion will inevitably be either used in another script, or wrapped with a bash one liner. PROGNAME=$(basename $0) function error_exit { # ---------------------------------------------------------------- # Function for exit due to fatal program error # Accepts 1 argument: # string containing descriptive error message # ---------------------------------------------------------------- echo "${PROGNAME}: ${1:-"Unknown

Testing for exit codes Earlier we used the $?

Ubuntu Ubuntu Insights Planet Ubuntu Activity Page Please read before SSO login Advanced Search Forum The Ubuntu Forum Community Ubuntu Specialised Support Development & Programming Programming Talk [SOLVED] Make shell script The return status is 0 unless local is used outside a function, an invalid name is supplied, or name is a readonly variable. perhaps this must be reported as a bug/wish to bash developers The answer is definitely no! Bash Script Exit If No Arguments Checking the exit status There are several ways you can get and respond to the exit status of a program.

if [ $filename = "foo" ]; will fail if $filename contains a space. When this is actually a calculation stored in a variable for later, and the value is set to blank, this may then cause later problems. is_shell_attribute_set e; then set -e e_was_set=0 fi "$cmd" "[email protected]" & wait $! || { exit_code=$? } if [ "$e_was_set" = 0 ] && is_shell_attribute_set e; then set +e fi if [ weblink What are the holes on the sides of a computer case frame for?

vBulletin ©2000 - 2016, Jelsoft Enterprises Ltd. Which is a useful feature when you're writing some common function that you will later source and use from other scripts. use the [] for that. Removing if: #!/bin/bash set -e # exit on any error readonly a=(1 2) # A syntax error is here: (( "${a[#]}" == 2 )) echo status $?

Options share|improve this answer edited Aug 22 at 4:52 Djidiouf 309 answered May 18 at 12:43 Mykhaylo Adamovych 4,84094063 add a comment| Your Answer draft saved draft discarded Sign up Second, the ${a[#]} is weird and its is why is giving errors... Fortunately bash provides you with set -u, which will exit your script if you try to use an uninitialised variable.