unix command - what happens under the hood


 
Thread Tools Search this Thread
Top Forums UNIX for Dummies Questions & Answers unix command - what happens under the hood
# 1  
Old 08-27-2009
unix command - what happens under the hood

Hello everyone,

When I run the command: rm adkjad (assuming the file adkjad doesn't exist), I get the following message:

adkjad: No such file or directory

I want to run this command, but I want a succesful return code whether the file is there or not.

I tried: rm adkjad 2> /dev/null , redirecting stderr to never never land, but I still get some type of negative return code.

Is there some other output(I am unware of) that I can send to /dev/null also?

Thanks in advance.

Robert
# 2  
Old 08-27-2009
what do you mean by negative return code???
according to me you should get 2 as return code ($?)
# 3  
Old 08-27-2009
I actually issue this command from another piece of software(which sends the command to the unix server - and gets a success or fail response). Unfortunately, even redirecting stderr(rm adkjad 2> /dev/null), the software I am using still gets a return code of 2, causing it to stop processing. Not sure how to get a success response regardless if rm command is succesful or not.

thx
# 4  
Old 08-27-2009
I think by "negative" you mean not 0?

Sending something to standard error, or anywhere else doesn't change the return code of a command.

Code:
rm noSuchFile
 
rm:  cannot lstat `noSuchFile`: No such file or directory
 
echo $?
 
1

Code:
rm noSuchFile | bc
 
rm:  cannot lstat `noSuchFile`: No such file or directory
 
echo $?
 
0

(this command makes no sense, but it also doesn't return a "negative" return code - the result of bc is 0, and that's what's returned, not the result of rm, in this case)
# 5  
Old 08-27-2009
Or something like:

Code:
rm adkjad 2> /dev/null ||  echo " " >/dev/null

# 6  
Old 08-27-2009
Quote:
Originally Posted by scottn
Code:
rm noSuchFile | bc
 
rm:  cannot lstat `noSuchFile`: No such file or directory
 
echo $?
 
0

(this command makes no sense, but it also doesn't return a "negative" return code - the result of bc is 0, and that's what's returned, not the result of rm, in this case)
good idea!
a slight alternative:
Code:
rm noSuchFile 2>/dev/null| :

# 7  
Old 08-27-2009
Quote:
Originally Posted by robert4732
Hello everyone,

When I run the command: rm adkjad (assuming the file adkjad doesn't exist), I get the following message:

adkjad: No such file or directory

I want to run this command, but I want a succesful return code whether the file is there or not.

I tried: rm adkjad 2> /dev/null , redirecting stderr to never never land, but I still get some type of negative return code.

Is there some other output(I am unware of) that I can send to /dev/null also?

Thanks in advance.

Robert
I like to use "rm -f" - the -f is force the remove, best used in batch jobs.

If the file is there or not, it will be removed and return a "0" status code.

However, if for some reason, you cannot delete the file (wrong ownership of the directory), it will return a bad code.
 
Login or Register to Ask a Question

Previous Thread | Next Thread

9 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

UNIX command to copy files from Windows to UNIX box

Hi Folks, I have a file name abc.xml in my windows machine at the location c:\ytr\abc.xml which I want to place at the unix box machine inside cde directory.. at the following location that is /opt/app/cde/ now the credentials of unix box are abc345 -->(dummyid) ftyiu88--->(dummy passwd) ... (4 Replies)
Discussion started by: punpun66
4 Replies

2. Shell Programming and Scripting

Specify an entire UNIX command as a command line argument

I'm trying to write a bash script called YN that looks like the following YN "Specify a question" "doThis" "doThat" where "doThis" will be executed if the answer is "y", otherwise "doThat". For example YN "Do you want to list the file dog?" "ls -al dog" "" Here's my attempt... (3 Replies)
Discussion started by: LeoKSimon
3 Replies

3. UNIX Desktop Questions & Answers

Can Unix access Windows' File through Command Prompt in Unix

Hi all, I wish to know whether Unix can access window's file in Unix's terminal? Apart from that, how to copy files or share files between Window and Unix? I get to know of secure copy, however, my company's Unix does not support the feature of secure copy? Any other method for me to share/... (5 Replies)
Discussion started by: jessy83
5 Replies

4. UNIX for Dummies Questions & Answers

New to Unix command line and have a question about the "sort" command

I am going through the Unix Made Easy second edition book by John Muster. So far it's been very informative and I can tell it may be a bit out of date. In one of the exercises it talks about the "sort" command and using it to sort column's of data etc. The "sort" command has changed a bit and... (1 Reply)
Discussion started by: budfoxcat
1 Replies

5. UNIX for Advanced & Expert Users

unix command : how to insert text at the cursor location via command line?

Hi, Well my title isn't very clear I think. So to understand my goal: I have a script "test1" #!/bin/bash xvkbd -text blabla with xbindkeys, I bind F5 key in order it runs my test1 script So when I press F5, test1 runs. I'm under Emacs/Vi and I press F5 in order to have "blabla" be... (0 Replies)
Discussion started by: xib.be
0 Replies

6. Shell Programming and Scripting

assign a command line argument and a unix command to awk variables

Hi , I have a piece of code ...wherein I need to assign the following ... 1) A command line argument to a variable e.g origCount=ARGV 2) A unix command to a variable e.g result=`wc -l testFile.txt` in my awk shell script When I do this : print "origCount" origCount --> I get the... (0 Replies)
Discussion started by: sweta_doshi
0 Replies

7. HP-UX

How to use more than one MPE command STREAM with Unix command in a single shell?

Hello, I have problem in writing the shell script involving MPE command STREAM related to HP-UX and Unix command. Script is sh "nlshCMD 'STREAM <job name1>' | 'SHOWJOB' | grep $HPJOBNUM" sh "nlshCMD 'STREAM <job name2>' | 'SHOWJOB' | grep $HPJOBNUM" sh "nlshCMD 'STREAM <job name3>' |... (1 Reply)
Discussion started by: bosskr
1 Replies

8. Shell Programming and Scripting

How to use more than one MPE command STREAM with Unix command in a single shell?

Hello, I have problem in writing the shell script involving MPE command STREAM related to HP-UX and Unix command. Script is sh "nlshCMD 'STREAM <job name1>' | 'SHOWJOB' | grep $HPJOBNUM" sh "nlshCMD 'STREAM <job name2>' | 'SHOWJOB' | grep $HPJOBNUM" sh "nlshCMD 'STREAM <job name3>' |... (0 Replies)
Discussion started by: bosskr
0 Replies

9. UNIX for Dummies Questions & Answers

wc command help.... and other unix command....... urgent

hi all. thanks for looking i am doing some homework. one question is that when type wc and then how to tell the program that we have finished entering data? also why do some operating systems report 22 as the number of bytes in the file above, while others only 20? thanks so much,... (1 Reply)
Discussion started by: dashi2k
1 Replies
Login or Register to Ask a Question