I've got a question regarding error handling in shell scripts. My background is mainly object oriented programming languages, but for a year or so I've been doing more and more (bash) shell scripting (which I quite enjoy by the way).
To handle errors in my scripts I often find myself doing something like:
In many cases the <handle error> is the same for the commands executed, so you end up duplicating code. Thus I think it would be better to encapsulate this code in a function, e.g.
And execute commands by calling this function:
Furthermore, the function can easily be enhanced to write the command as well as the command output and return code to a log file:
I found this quite handy to handle errors in my scripts. If you write command, output and return code to a log file, it also makes it quite easy to investigate problems with scripts that run in the background.
Now my question is:
How is that as a practise? Is it common? Or would it be considerd as bad and if so why? Has the bash already got something like this build in? (E.g. there might be an exit on fail option; I also know that you can start scripts with an option which outputs the commands which are being executed).
How do the experienced people here do the error handling in their scripts?
Hi,
I face some problem with handling of nulls. I declare a variable - say i - and intialise to 0. Later I read it from console, wherein if I dont give any variable and press return key, I get this error:
"0403-004 Specify a parameter with this command"
Is there anyway to handle this error?
... (3 Replies)
Hi,
I am using few ISQL statements to update and delete from a few tables in sybase, now i want to roll back the transaction when any of the statements fail.How i can i capture these errors in the shell scripts.Please advise.
Thanks,
Gopi (4 Replies)
I have a shell script, which calls a load script to load a database. How can i handle errors in Unix(similar to 'error level' in Batch scripts)? I am trying to use 'mailx' to send a Success/failure message based on the error level returned by the load script.
I have already used an error log... (2 Replies)
What i need to do is when the database connection is not successful , the script should move to next list i.e skip the current.
But when i do this -
if ; then
break;
fi
The script break but it goes to the condition -
if ; then
for LIST in $LISTS
do
for TABLE in $TABLES
do... (2 Replies)
Hi all, i have more questions but its all about variables so lets begin
1st, is possible to list all variables ?
Command env display only shell variables, but what if i declared another variable? Command set display more variables but not defined by me.
2nd, what difference is between set... (24 Replies)
Hello,
I have written a shell script and suppose there is any error in the script. How i can do exception handling in shell script.for example i have below code
sqlplus -s <<uid>>/<<pwd>>@<<$ORACLE_SID>> <<EOF > 1_pid1.log
set pagesize 0
set feedback off
set heading off
set linesize 200... (1 Reply)
Hi,
I have a shell script confug-msys.sh which callls config-common.sh. When run from command prompt,these work fine but give the below error when i try to run from code-blocks
line 7: --without-contrib: command not found
...Also I am unable to understand what the second script does...... (4 Replies)
Hi Friend,
Could you please provide me with some tutorial for Advanced Exception handling in C++, mainly set_terminate() and set_unexpected() functions?
Please find the details below:
OS: Unix
Compiler: gcc.
Thanks. :)
Awesome001 (0 Replies)
Dear all
I have shell script where files have been organized into directory, i pass the directory name and it shold pick all the files within the directory and move to differnet path.
When i run the scripts it doesn't move and come out with error and i am not able to understand it
the... (2 Replies)
Hi ,
My Script work as below
1-
On server 1
execute script1.sh ,
through this script one parameter file is generated as file.txt this is to transfer on server 2
2-
After reaching on server2 other shell script script2.sh execute using parameter file file.txt
This generate file... (1 Reply)
Discussion started by: kaushik02018
1 Replies
LEARN ABOUT OSX
getopt
GETOPT(1) BSD General Commands Manual GETOPT(1)NAME
getopt -- parse command options
SYNOPSIS
args=`getopt optstring $*` ; errcode=$?; set -- $args
DESCRIPTION
The getopt utility is used to break up options in command lines for easy parsing by shell procedures, and to check for legal options.
Optstring is a string of recognized option letters (see getopt(3)); if a letter is followed by a colon, the option is expected to have an
argument which may or may not be separated from it by white space. The special option '--' is used to delimit the end of the options. The
getopt utility will place '--' in the arguments at the end of the options, or recognize it if used explicitly. The shell arguments ($1 $2
...) are reset so that each option is preceded by a '-' and in its own shell argument; each option argument is also in its own shell argu-
ment.
EXAMPLES
The following code fragment shows how one might process the arguments for a command that can take the options -a and -b, and the option -o,
which requires an argument.
args=`getopt abo: $*`
# you should not use `getopt abo: "$@"` since that would parse
# the arguments differently from what the set command below does.
if [ $? != 0 ]
then
echo 'Usage: ...'
exit 2
fi
set -- $args
# You cannot use the set command with a backquoted getopt directly,
# since the exit code from getopt would be shadowed by those of set,
# which is zero by definition.
for i
do
case "$i"
in
-a|-b)
echo flag $i set; sflags="${i#-}$sflags";
shift;;
-o)
echo oarg is "'"$2"'"; oarg="$2"; shift;
shift;;
--)
shift; break;;
esac
done
echo single-char flags: "'"$sflags"'"
echo oarg is "'"$oarg"'"
This code will accept any of the following as equivalent:
cmd -aoarg file file
cmd -a -o arg file file
cmd -oarg -a file file
cmd -a -oarg -- file file
SEE ALSO sh(1), getopt(3)DIAGNOSTICS
The getopt utility prints an error message on the standard error output and exits with status > 0 when it encounters an option letter not
included in optstring.
HISTORY
Written by Henry Spencer, working from a Bell Labs manual page. Behavior believed identical to the Bell version. Example changed in FreeBSD
version 3.2 and 4.0.
BUGS
Whatever getopt(3) has.
Arguments containing white space or embedded shell metacharacters generally will not survive intact; this looks easy to fix but isn't. Peo-
ple trying to fix getopt or the example in this manpage should check the history of this file in FreeBSD.
The error message for an invalid option is identified as coming from getopt rather than from the shell procedure containing the invocation of
getopt; this again is hard to fix.
The precise best way to use the set command to set the arguments without disrupting the value(s) of shell options varies from one shell ver-
sion to another.
Each shellscript has to carry complex code to parse arguments halfway correcty (like the example presented here). A better getopt-like tool
would move much of the complexity into the tool and keep the client shell scripts simpler.
BSD April 3, 1999 BSD