Consider the case where I have a very long bash script with several commands. Is there a simple way to check the exit status for ALL of them easily. So if there's some failure I can show which command has failed and its return code.
I mean, I don't want to use the test for each one of them checks like the following:
my_command
if [ $status -ne 0 ]; then
#error case
echo "error while executing " my_command " ret code:" $?
exit 1
fi
You can do trap "cmd" ERR, which invokes cmd when a command fails. However this solution has a couple of drawbacks. For example, it does not catch a failure inside a pipe.
In a nutshell, you are better off doing your error management properly, on a case by case basis.
You can write a function that launches:
function test {
"$#"
local status=$?
if [ $status -ne 0 ]; then
echo "error with $1" >&2
fi
return $status
}
test command1
test command2
One can test the value of $? or simply put set -e at the top of the script which will cause it to exit upon any command which errors.
#!/bin/sh
set -xe
my_command1
# never makes it here if my_command1 fails
my_command2
Related
I run a Jenkins pipeline job with Groovy. The Groovy calls bash scripts for each step.
I want to fail the whole job when something in the way has errors.
For Groovy I use the returnStatus: true.
For Bash I use set -e.
But a bash script with set -e, does not exit if, for example, a while statement has errors. This is what should actually happen, according to the Linux manual page for 'set'.
I would like to know how to exit immediately in that scenario.
The script:
[jenkins-user#jenkins ~]$ cat script.sh
#!/bin/bash
set -xe
FILE=commands.txt
echo "echos before while"
# Run the commands in the commands file
while read COMMAND
do
$COMMAND
done < $FILE
echo $?
echo "echos after faulty while"
Let's say 'commands.txt' doesn't exist.
Running script:
[jenkins-user#jenkins ~]$ sh script.sh
echos before while
script.sh: line 13: commands.txt: No such file or directory
1
echos after faulty while
[jenkins-user#jenkins ~]$ echo $?
0
Although the while statement returns exit code 1, the script continues and ends successfully, as checked right after, with echo $?.
This is how I force the Groovy to fail, after a step with bash/python/etc command/script returns a none-zero exit code:
pipeline {
agent any
stages {
stage("A") {
steps {
script {
def rc = sh(script: "sh A.sh", returnStatus: true)
if (rc != 0) {
error "Failed, exiting now..."
}
}
}
}
}
}
First question, how can I make the SHELL script to fail when the while/if/etc statements have errors? I know I can use command || exit 1 but it doesn't seem elegant if I have dozens of statements like this in the script.
Second question, is my Groovy error handling correct? Can anyone suggest an event better way? Or maybe there is a Jenkins plugin/official way to do so?
First question this link may be helpful Aborting a shell script if any command returns a non-zero value
Second question: You can improve your error handling using try and catch for exception handling.
try{
def rc = sh(script: "sh A.sh", returnStatus: true)
if (rc != 0) {
error "Failed, exiting now..."
}
}
catch (Exception er){
errorMessage = er.getMessage();
}
About the Bash script.
Your issue is that the fail redirection does not abort the bash script, despite the use of set -e. I was surprised my-self. But it's my first disappointment about set -e, so now I consider to not trust it and I abuse of stuff like $command || exit 1 ...
Here you can do the following:
set -xe -o pipefail
cat $FILE | while read command; do $command ; done
But the whole loop should be simplified into:
bash $FILE
Why don't you just use the while exit code and return it? (See this modified version of your script, the last lines)
[jenkins-user#jenkins ~]$ cat script.sh
#!/bin/bash
set -xe
FILE=commands.txt
echo "echos before while"
# Run the commands in the commands file
while read COMMAND
do
$COMMAND
done < $FILE
status=$?
echo "echos after faulty while"
exit $status
[jenkins-user#jenkins ~]$ cat script.sh
#!/bin/bash
set -xe
FILE=commands.txt
echo "echos before while"
# Run the commands in the commands file
while read COMMAND
do
$COMMAND
done < $FILE
echo $?
echo "echos after faulty while"
When yor perform a echo $? after this script it will always be 0, because the last command was echo "echos after faulty while" you can ad an exit 1 at the end of your script. In exit 1 the number 1 will be the error code, you can use other. So the script will be
[jenkins-user#jenkins ~]$ cat script.sh
#!/bin/bash
set -xe
FILE=commands.txt
echo "echos before while"
# Run the commands in the commands file
while read COMMAND
do
$COMMAND
done < $FILE
echo $?
exit 1
I have bash script with many lines of code and I need run it while it returns $? == 0, but in case if it has error I need stop it and exit with code 1?
The question is how to do it?
I tried to use set -e command, but Jenkins does not marks build as failed, for him it looks like Success
I also need to get the Error message to show it in my Jenkins log
I managed to get error code(in my case it will be 126), but how to get error message?
main file
fileWithError.sh
rc=$?; if [[ $rc != 0 ]]; then
echo "exit {$rc} ";
fi
fileWithError.sh
#!/bin/sh
set -e
echo "Test"
agjfsjgfshgd
echo "Test2"
echo "Test3"
Just add the command set -e to the beginning of the file
This should look something similar to this
#!/bin/sh
set -e
#...Your code...
I think you just want:
#!/bin/sh
while fileWithError.sh; do
sleep 1;
done
echo fileWithError.sh failed!! >&2
Note that if the script is written well, then the echo is
redundant as fileWithError.sh should have written a decent
error message already. Also, the sleep may not be needed, but is useful to prevent a fast loop if the script succeeds quickly.
You can get the explicit return value, but it requires a bit of refactoring.
#!/bin/sh
true
while test $? = 0; do fileWithError.sh; done
echo fileWithError.sh failed with status $?!! >&2
since the return value of the while script will be the
return value of sleep in the first construction.
Its not quite easy to get an error code only.
How about this ...
#!/bin/bash
Msg=$(fileWithError.sh 2>&1) # redirect all error messages to stdout
if [ "$?" -ne 0 ] # Not Equal
then
echo "$Msg"
exit 1
fi
exit 0
You catch all messages created by fileWithError.sh and if the programm returned an error code then you have the error message already saved in a variable.
But this will make a disadvantage, because you will temporary store all messages created by fileWithError.sh till the error appears.
You can filter the error message with echo "$Msg" |tail -n 1, but its not 100% save.
You should also do some changes in fileWithError.sh...
Switch set -e with trap "exit 1" ERR. this will close the script on errors.
Hope this will help.
I'm trying to figure out what this means/how $? gets populated in linux, I tried doing a search but if someone could clarify that would be great:
exitstat=$?
if [ $exitstat -ne 0 ]
then
echo -e "Could Not Extract"
echo -e "Aborting Script `date`"
exit $exitstat
fi
The code above that is:
_xfile << %% 2> /files/thefile-7000.log | _afile -x -r 10 2> /files/thefile-7000.log > /files/thefile.7000
OperatorHigh = $finalnumber
%%
$? expands to the exit status of the most recent foreground command.
Since your prior command is a pipeline, the exit status is that of the last command in the pipeline -- in this case, _afile -- unless the pipefail shell option is set, in which case failures elsewhere in the pipeline can also make exit status nonzero.
My shell script is as shown below:
#!/bin/bash
# Make sure only root can run our script
[ $EUID -ne 0 ] && (echo "This script must be run as root" 1>&2) || (exit 1)
# other script continues here...
When I run above script with non-root user, it prints message "This script..." but it doe not exit there, it continues with the remaining script. What am I doing wrong?
Note: I don't want to use if condition.
You're running echo and exit in subshells. The exit call will only leave that subshell, which is a bit pointless.
Try with:
#! /bin/sh
if [ $EUID -ne 0 ] ; then
echo "This script must be run as root" 1>&2
exit 1
fi
echo hello
If for some reason you don't want an if condition, just use:
#! /bin/sh
[ $EUID -ne 0 ] && echo "This script must be run as root" 1>&2 && exit 1
echo hello
Note: no () and fixed boolean condition. Warning: if echo fails, that test will also fail to exit. The if version is safer (and more readable, easier to maintain IMO).
I think you need && rather than||, since you want to echo and exit (not echo or exit).
In addition (exit 1) will run a sub-shell that exits rather than exiting your current shell.
The following script shows what you need:
#!/bin/bash
[ $1 -ne 0 ] && (echo "This script must be run as root." 1>&2) && exit 1
echo Continuing...
Running this with ./myscript 0 gives you:
Continuing...
while ./myscript 1 gives you:
This script must be run as root.
I believe that's what you were looking for.
I would write that as:
(( $EUID != 0 )) && { echo "This script must be run as root" 1>&2; exit 1; }
Using { } for grouping, which executes in the current shell. Note that the spaces around the braces and the ending semi-colon are required.
I have a 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?
For example,
dosomething1
if [[ $? -ne 0 ]]; then
exit 1
fi
dosomething2
if [[ $? -ne 0 ]]; then
exit 1
fi
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 manual on the "set" internal command for more details.
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. I personally start almost all portable shell scripts with set -e.
If I'm working with bash specifically, I'll start with
set -Eeuo pipefail
This covers more error handling in a similar fashion. I consider these as sane defaults for new bash programs. Refer to the bash manual for more information on what these options do.
To add to the accepted answer:
Bear in mind that set -e sometimes is not enough, specially if you have pipes.
For example, suppose you have this script
#!/bin/bash
set -e
./configure > configure.log
make
... which works as expected: an error in configure aborts the execution.
Tomorrow you make a seemingly trivial change:
#!/bin/bash
set -e
./configure | tee configure.log
make
... and now it does not work. This is explained here, and a workaround (Bash only) is provided:
#!/bin/bash
set -e
set -o pipefail
./configure | tee configure.log
make
The if statements in your example are unnecessary. Just do it like this:
dosomething1 || exit 1
If you take Ville Laurikari's advice and use set -e then for some commands you may need to use this:
dosomething || true
The || true will make the command pipeline have a true return value even if the command fails so the the -e option will not kill the script.
If you have cleanup you need to do on exit, you can also use 'trap' with the pseudo-signal ERR. This works the same way as trapping INT or any other signal; bash throws ERR if any command exits with a nonzero value:
# Create the trap with
# trap COMMAND SIGNAME [SIGNAME2 SIGNAME3...]
trap "rm -f /tmp/$MYTMPFILE; exit 1" ERR INT TERM
command1
command2
command3
# Partially turn off the trap.
trap - ERR
# Now a control-C will still cause cleanup, but
# a nonzero exit code won't:
ps aux | grep blahblahblah
Or, especially if you're using "set -e", you could trap EXIT; your trap will then be executed when the script exits for any reason, including a normal end, interrupts, an exit caused by the -e option, etc.
The $? variable is rarely needed. The pseudo-idiom command; if [ $? -eq 0 ]; then X; fi should always be written as if command; then X; fi.
The cases where $? is required is when it needs to be checked against multiple values:
command
case $? in
(0) X;;
(1) Y;;
(2) Z;;
esac
or when $? needs to be reused or otherwise manipulated:
if command; then
echo "command successful" >&2
else
ret=$?
echo "command failed with exit code $ret" >&2
exit $ret
fi
Run it with -e or set -e at the top.
Also look at set -u.
On error, the below script will print a RED error message and exit.
Put this at the top of your bash script:
# BASH error handling:
# exit on command failure
set -e
# keep track of the last executed command
trap 'LAST_COMMAND=$CURRENT_COMMAND; CURRENT_COMMAND=$BASH_COMMAND' DEBUG
# on error: print the failed command
trap 'ERROR_CODE=$?; FAILED_COMMAND=$LAST_COMMAND; tput setaf 1; echo "ERROR: command \"$FAILED_COMMAND\" failed with exit code $ERROR_CODE"; put sgr0;' ERR INT TERM
An expression like
dosomething1 && dosomething2 && dosomething3
will stop processing when one of the commands returns with a non-zero value. For example, the following command will never print "done":
cat nosuchfile && echo "done"
echo $?
1
#!/bin/bash -e
should suffice.
I am just throwing in another one for reference since there was an additional question to Mark Edgars input and here is an additional example and touches on the topic overall:
[[ `cmd` ]] && echo success_else_silence
Which is the same as cmd || exit errcode as someone showed.
For example, I want to make sure a partition is unmounted if mounted:
[[ `mount | grep /dev/sda1` ]] && umount /dev/sda1