Visit Our UNIX and Linux User Community


trap


 
Thread Tools Search this Thread
Top Forums Shell Programming and Scripting trap
# 1  
Old 01-29-2009
trap

Hi

At the beginning of my script, i will create a file and at the end of the script i will delete that.

But i got to delete the file even if the process is forcefully killed, or server is rebooted...

I think i can make use of trap signal, but couldnt figure out how and where to use in my script.

What will be structure of the command?
# 2  
Old 01-29-2009
trap cannot "trap" all signals, for example SIGKILL is "immune" to a trap.

Near the top of your file:

Code:
#!/bin/ksh

trap "rm -f somefile; exit 1" INT  # you can add more signals here

will execute the command in quotes when CTRL/C -- SIGINT -- is sent to the process.
kill -l (that's the letter ELL) will show you the names of your signals. Be aware that not all signals need to be trapped nor can they be.
# 3  
Old 01-29-2009
If it's bash or ksh (maybe others too) you can use 'trap something 0', which will run on the virtual "EOF" signal.
# 4  
Old 01-29-2009
pludi is helpfully pointing out - you ought know that it is possible to make your trap statement do the cleanup on exit - in ksh anyway, I dunno about bash.
Code:
trap "rm -f somefile; exit " 0 INT QUIT SEGV BUS

# 5  
Old 01-29-2009
trap

Quote:
Originally Posted by jim mcnamara
trap cannot "trap" all signals, for example SIGKILL is "immune" to a trap.

Near the top of your file:

Code:
#!/bin/ksh

trap "rm -f somefile; exit 1" INT  # you can add more signals here

will execute the command in quotes when CTRL/C -- SIGINT -- is sent to the process.
kill -l (that's the letter ELL) will show you the names of your signals. Be aware that not all signals need to be trapped nor can they be.
Thankyou.
But what does 1 indicate. Is that the numeric form of signal.
Where can i find the other numeric forms of signals.

Previous Thread | Next Thread
Test Your Knowledge in Computers #398
Difficulty: Medium
HP-UX offers operating system-level virtualization features such as hardware partitions, isolated OS virtual partitions on cell-based servers, and HP Integrity Virtual Machines (HPVM) on all Integrity servers.
True or False?

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Trap

Hi Ppl, Need help $ cat trap.sh #!/bin/bash trap cleanup 1 2 3 15 cleanup() { echo “I was running \”$BASH_COMMAND\” when you interrupted me.” echo “Quitting.” exit 1 } while : do echo -en “hello. “ sleep 1 (3 Replies)
Discussion started by: heman96
3 Replies

2. Homework & Coursework Questions

VM trap may work differently than a pure install trap.

Use and complete the template provided. The entire template must be completed. If you don't, your post may be deleted! 1. The problem statement, all variables and given/known data: That is the last reply I received from my instructor, and I'm looking for some alternatives. When using... (2 Replies)
Discussion started by: newuser45
2 Replies

3. Shell Programming and Scripting

what does this 'trap' do?

trap "" 1 2 3 Thanks, -dog (1 Reply)
Discussion started by: landog
1 Replies

4. Shell Programming and Scripting

Cntl+z Trap is not detecting ??? Help required to add a trap detection ???

Hi folks, I have tried to add some trap detection in the below script....this script is used to monitor database activities...in a rather awkward way :rolleyes:.... The idea behind adding trap is that....this script creates lots of temporary files in the running folder to store the count... (1 Reply)
Discussion started by: frozensmilz
1 Replies

5. Shell Programming and Scripting

How to trap

I have a script #!/bin/ksh trap cleanup 20 cleanup() { cat $t.log echo Caught exit 1 } if ;then echo Found >>t.log exit 20 else echo Not found >>t.log exit 20 fi (5 Replies)
Discussion started by: thana
5 Replies

6. Shell Programming and Scripting

Trap

Hi All "Identify the behavior of traps, mechanism to implement traps in the snmp framework" What does it mean?? Can anybody explain.. Whats this Trap?? Thanx in Advance. (1 Reply)
Discussion started by: jeenat
1 Replies

7. UNIX for Advanced & Expert Users

Need help with trap

Hi Our problem is knowing: What is the "best" way of simulating a TRAP for ERR within a function, since we know this will not work directly with ksh93 and aix5. How can we save the error encountered in the function and then deal with it in the calling script? Thanks! (3 Replies)
Discussion started by: theteeth07
3 Replies

8. Shell Programming and Scripting

Building a better mouse trap, or How many lines of code does it take to trap a mouse?

Hello all, I'm hoping to get a little insight from some of the wily veterans amongst you. I've written a script to check for new outgoing files to our vendors located on our ssl server. It seems to be working ok, but the final question here, will be one of logic, and/or a better way to... (4 Replies)
Discussion started by: mph
4 Replies

9. Shell Programming and Scripting

trap

I'd like to use "trap" command on my unix machine sunOS 5.7. But somehow when I do "which trap" command, it's no where to be found. Any one knows how I can get it installed? Thanks!! (9 Replies)
Discussion started by: whatisthis
9 Replies

10. UNIX for Advanced & Expert Users

Need help with trap

My problem is this: I need to have a catch-all for my processes. An example would be, using a trap, in the parent, to catch any non-0 exit or invalid command (a way to catch core dumps would be cool, too) in not only the parent, but it's children and they're children. Not only that, but I also... (7 Replies)
Discussion started by: marc6057
7 Replies

Featured Tech Videos