OR'ing condition in script Post: 69843

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Top Forums Shell Programming and Scripting OR'ing condition in script Post 69843 by Just Ice on Wednesday 20th of April 2005 05:57:37 PM

04-20-2005

Registered User

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 #

Just Ice

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LEARN ABOUT DEBIAN

dh_usrlocal

DH_USRLOCAL(1)							     Debhelper							    DH_USRLOCAL(1)

NAME

       dh_usrlocal - migrate usr/local directories to maintainer scripts

SYNOPSIS

       dh_usrlocal [debhelperoptions] [-n]

DESCRIPTION

       dh_usrlocal is a debhelper program that can be used for building packages that will provide a subdirectory in /usr/local when installed.

       It finds subdirectories of usr/local in the package build directory, and removes them, replacing them with maintainer script snippets
       (unless -n is used) to create the directories at install time, and remove them when the package is removed, in a manner compliant with
       Debian policy. These snippets are inserted into the maintainer scripts by dh_installdeb. See dh_installdeb(1) for an explanation of
       debhelper maintainer script snippets.

       If the directories found in the build tree have unusual owners, groups, or permissions, then those values will be preserved in the
       directories made by the postinst script. However, as a special exception, if a directory is owned by root.root, it will be treated as if it
       is owned by root.staff and is mode 2775. This is useful, since that is the group and mode policy recommends for directories in /usr/local.

OPTIONS

       -n, --noscripts
	   Do not modify postinst/prerm scripts.

NOTES

       Note that this command is not idempotent. dh_prep(1) should be called between invocations of this command. Otherwise, it may cause multiple
       instances of the same text to be added to maintainer scripts.

CONFORMS TO

       Debian policy, version 2.2

SEE ALSO

       debhelper(7)

       This program is a part of debhelper.

AUTHOR

       Andrew Stribblehill <ads@debian.org>

9.20120909							    2011-09-12							    DH_USRLOCAL(1)

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