OR'ing condition in script


 
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# 1  
Old 04-19-2005
OR'ing condition in script

Hi,

I have the following requirement. I am building a product on linux. The final build executables and libraries are all in different directories. I am writing a release script to collect all these final build items into a directory in /home/$USER/release.

I have the following condition:

Code:
if [ -f $DEVMGR/$FILE -o -f $DEVMGRCONSOLE/$FILE ] ; then

Now I need to copy which ever above file is present to /home/$USER/release. Both conditions will never be true at any time. Only 1 will be. How do I incorporate that ?

Your inputs please.

Vino
# 2  
Old 04-19-2005
if you're absolutely certain that both conditions can never be true at the same time, your "if" condition should suffice ... otherwise, you can add another check to make sure that only 1 of the conditions is true at any time ...
# 3  
Old 04-19-2005
try this one ...
Code:
if [ -f $DEVMGR/$FILE -o -f $DEVMGRCONSOLE/$FILE ]
then
    if [ -f $DEVMGR/$FILE ]
    then
        cp -p $DEVMGR/$FILE /home/$USER/release
    else
        cp -p $DEVMGRCONSOLE/$FILE /home/$USER/release
    fi
fi

# 4  
Old 04-19-2005
I want to avoid that second if..else block. Is there anyway ?

I feel not. What say ?

Vino
# 5  
Old 04-19-2005
Code:
if [ -f $DEVMGR/$FILE -o -f $DEVMGRCONSOLE/$FILE ]
then
    cp -p $DEVMGR/$FILE /home/$USER/release 2> /dev/null
    cp -p $DEVMGRCONSOLE/$FILE /home/$USER/release 2> /dev/null
fi

# 6  
Old 04-19-2005
Ice,

Thanks for the solutions. Works good.

One question though. Why the -p ? Wouldn't -f work well ?

Yes the man pages do tell that permissions will be preserved. What is the significance of -p in this case ? Am I missing something ?

Vino
# 7  
Old 04-20-2005
per the cp man page ...
Quote:
-f Unlink. If a file descriptor for a destination file
cannot be obtained, attempt to unlink the destination
file and proceed.
...

/usr/bin/cp
The following option is supported for /usr/bin/cp only:

-p Preserve. cp duplicates not only the contents of
source_file, but also preserves the owner and group
id, permissions modes, modification and access time,
and ACLs if applicable. Note that the command may fail
if ACLs are copied to a file system that does not sup-
port ACLs. The command will not fail if unable to
preserve modification and access time or permission
modes. If unable to preserve owner and group id, cp
will not fail, and it will clear S_ISUID and S_ISGID
bits in the target. cp will print a diagnostic message
to stderr and return a non-zero exit status if unable
to clear these bits.

In order to preserve the owner and group id, permis-
sion modes, and modification and access times, users
must have the appropriate file access permissions;
this includes being superuser or the same owner id as
the destination file.
however, i've never really used the "-f" option --- like most other esoteric options of other commands that are good to know but not required for basic stuff --- so i don't actually understand the unlink statement ... maybe one of the hardcore c programmers here can explain it better ...

do look at this test here and you can decide what it is you need ...
Code:
root_mybox:/tmp # cp -p /etc/profile testprofile
root_mybox:/tmp # ls -l /etc/profile testprofile
-rw-r--r--   1 root     sys          920 Dec  3 19:04 /etc/profile
-rw-r--r--   1 root     sys          920 Dec  3 19:04 testprofile
root_mybox:/tmp # cp -f /etc/profile testprofile1
root_mybox:/tmp # ls -l /etc/profile testprofile1
-rw-r--r--   1 root     sys          920 Dec  3 19:04 /etc/profile
-rw-r--r--   1 root     other        920 Apr 20 17:51 testprofile1
root_mybox:/tmp #

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