Re: [SLUG] Just sharing a gotcha with "rsync" that caused me big trouble ...extra
On Tue, Dec 16, 2008 at 07:34:10PM +1100, Patrick Lesslie wrote: > On Sun, Dec 14, 2008 at 11:38:10PM +1100, R.G.Salisbury wrote: > > Like the deal with the trailing slash . which can cause issues --- > > (often put there by bashs tab completion). > > I like putting a "*" after a trailing slash as i find it more intuitive. > > The trailing slash or not option is handy once you know about it, but > confusing until you do. > > It also makes a difference whether you put a "*" after the trailing slash > or not, since the shell interpolates the "*" and doesn't include hidden > files, which may be important for a home directory backup for example. Here's an idiom which has saved me thinking too hard; use . as the source: cd /whatever/source/ && rsync -a . /some/destination/directory It will work the same whether source is just source or source/ It will fail nicely if /some/destination/directory doesn't exist It will work the same with the same sort of errors if you use cp -a instead of rsync -a. It picks up .files in source as well which rsync source/* /some/dest/ doesn't. Matt -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Just sharing a gotcha with "rsync" that caused me big trouble ...extra
On Tue, Dec 16, 2008 at 7:13 PM, R.G.Salisbury wrote: > > - Original Message - From: "James Polley" > To: "R.G.Salisbury" > Cc: > Sent: Tuesday, December 16, 2008 4:35 PM > Subject: Re: [SLUG] Just sharing a gotcha with "rsync" that caused me big > trouble ...extra > > >> There is nothing more worthy of contempt than a man who quotes himself >> - Zhasper, 2004 What was that idiot thinking, putting his sig at the top of the.. wait, that was me. never mind. >> >> >> >> On Sun, Dec 14, 2008 at 11:38 PM, R.G.Salisbury >> wrote: >>> >>> Just sharing a gotcha with "rsync" that caused me big trouble ... >>> >>> what's nasty about rsync ?.. >>> .. which may cause devastating consequences. >>> >>> rsync is in my opion the best thing since sliced bread... but be careful. >>> >>> >>> >>> CLI commands -- cp, rcp, scp, rsync, all have similarites >>> BUT there are some nasty gotcha's when switching from one to another. >>> >>> You probably noticed some oddities , but had worked around it. (with the >>> help of an error message) >>> Without an error message you may had come to grief. >>> >>> Consider .. >>> >>> Scenario: >>> For whatever reason -- you want to restore the /etc directory from a >>> local backup. >>> Lets just use a simple example.. >>> >>> "cp" should handle this. >>> "rsync" should also should handle this. >>> >>> But "cp" is your friend if you make an error ... "rsync" is not. >>> >>> OK There is NO source or destinantion directory "ets" but you >>> make a >>> typo "ets" instead of "etc" >>> >>> "cp" will give you an error message whereas "rsync" will do what is >>> not >>> intended and you will be *unaware* >>> >>> So the following commands >>> >>> [r...@localhost ~]# cp -a/backup/etc/* /ets >>> >>> [r...@localhost ~]# rsync -a/backup/etc/* /ets >>> >>> >>> "cp" will error out telling you that the target is not a directory >> >> if you use cp -ar /backup/etc /etc, cp, won't give you a warning. > > Thanks for reinforcing my point James > cp -ar /backup/etc /etc > > will produce/etc/etc > & the data is in the wrong place DISASTER again! Disaster? Not really - I've just got a spare copy around now, which I can easily remove with a quick rm -rf /etc/etc* - but wait, that really could be a disaster. It sounds like we're agreed: double-check your commandline; do a dry-run if you can, get verbose output *and* pay attention to it, and then make sure you check the results afterwards. Oh, and always have a backup, because sooner or later you're going to screw up anyway. > >> >>> whereas >>> "rsync will SILENTLY create the dir (ets) and populate it. >> >> so add a "-v" and you'll see some output telling you "created directory >> ets". >> >> This is not unusual. Most unix commands only bother you when there's a >> problem, and there was no problem here. >> >> Of course, you're going to ignore that output anyway, aren't you... >>> >>> So if you didn't check the result disaster beckons. >> >> So check it. >>> >>> Note that the creation of directories occur without a trailing slash on >>> the source. >>> But in that instance directory created is the name of the source >>> directory. >> >> Note that blindly using *any* command, without paying attention, >> without understanding what you're doing, can lead to disaster. This is >> a PEBKAC, not a fault of the tool. >> >>> >>> >>> I have found some other gotchas .. But do be aware of this (nasty) >>> feature. >>> Won't go into detail but some are . >> >> No, please do! >> >>> Like the deal with the trailing slash . which can cause issues --- >>> (often put there by bashs tab completion). >>> I like putting a "*" after a trailing slash as i find it more intuitive. >>> Also creating a new dir once -- but not twice.. >>> Blah..Blah >>> >>> Cheers >>> Roger >>> -- >>> SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ >>> Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html >>> > > -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Just sharing a gotcha with "rsync" that caused me big trouble ...extra
On Sun, Dec 14, 2008 at 11:38:10PM +1100, R.G.Salisbury wrote: > Like the deal with the trailing slash . which can cause issues --- > (often put there by bashs tab completion). > I like putting a "*" after a trailing slash as i find it more intuitive. The trailing slash or not option is handy once you know about it, but confusing until you do. It also makes a difference whether you put a "*" after the trailing slash or not, since the shell interpolates the "*" and doesn't include hidden files, which may be important for a home directory backup for example. Patrick Lesslie -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Just sharing a gotcha with "rsync" that caused me big trouble ...extra
- Original Message - From: "James Polley" To: "R.G.Salisbury" Cc: Sent: Tuesday, December 16, 2008 4:35 PM Subject: Re: [SLUG] Just sharing a gotcha with "rsync" that caused me big trouble ...extra There is nothing more worthy of contempt than a man who quotes himself - Zhasper, 2004 On Sun, Dec 14, 2008 at 11:38 PM, R.G.Salisbury wrote: Just sharing a gotcha with "rsync" that caused me big trouble ... what's nasty about rsync ?.. .. which may cause devastating consequences. rsync is in my opion the best thing since sliced bread... but be careful. CLI commands -- cp, rcp, scp, rsync, all have similarites BUT there are some nasty gotcha's when switching from one to another. You probably noticed some oddities , but had worked around it. (with the help of an error message) Without an error message you may had come to grief. Consider .. Scenario: For whatever reason -- you want to restore the /etc directory from a local backup. Lets just use a simple example.. "cp" should handle this. "rsync" should also should handle this. But "cp" is your friend if you make an error ... "rsync" is not. OK There is NO source or destinantion directory "ets" but you make a typo "ets" instead of "etc" "cp" will give you an error message whereas "rsync" will do what is not intended and you will be *unaware* So the following commands [r...@localhost ~]# cp -a/backup/etc/* /ets [r...@localhost ~]# rsync -a/backup/etc/* /ets "cp" will error out telling you that the target is not a directory if you use cp -ar /backup/etc /etc, cp, won't give you a warning. Thanks for reinforcing my point James cp -ar /backup/etc /etc will produce/etc/etc & the data is in the wrong place DISASTER again! whereas "rsync will SILENTLY create the dir (ets) and populate it. so add a "-v" and you'll see some output telling you "created directory ets". This is not unusual. Most unix commands only bother you when there's a problem, and there was no problem here. Of course, you're going to ignore that output anyway, aren't you... So if you didn't check the result disaster beckons. So check it. Note that the creation of directories occur without a trailing slash on the source. But in that instance directory created is the name of the source directory. Note that blindly using *any* command, without paying attention, without understanding what you're doing, can lead to disaster. This is a PEBKAC, not a fault of the tool. I have found some other gotchas .. But do be aware of this (nasty) feature. Won't go into detail but some are . No, please do! Like the deal with the trailing slash . which can cause issues --- (often put there by bashs tab completion). I like putting a "*" after a trailing slash as i find it more intuitive. Also creating a new dir once -- but not twice.. Blah..Blah Cheers Roger -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Just sharing a gotcha with "rsync" that caused me big trouble ...extra
On Tue, Dec 16, 2008 at 16:35, James Polley wrote: > Note that blindly using *any* command, without paying attention, > without understanding what you're doing, can lead to disaster. This is > a PEBKAC, not a fault of the tool. Furthermore, rsync has airbags: -n, --dry-run perform a trial run with no changes made Cheers, h -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Just sharing a gotcha with "rsync" that caused me big trouble ...extra
There is nothing more worthy of contempt than a man who quotes himself - Zhasper, 2004 On Sun, Dec 14, 2008 at 11:38 PM, R.G.Salisbury wrote: > Just sharing a gotcha with "rsync" that caused me big trouble ... > > what's nasty about rsync ?.. > .. which may cause devastating consequences. > > rsync is in my opion the best thing since sliced bread... but be careful. > > > > CLI commands -- cp, rcp, scp, rsync, all have similarites > BUT there are some nasty gotcha's when switching from one to another. > > You probably noticed some oddities , but had worked around it. (with the > help of an error message) > Without an error message you may had come to grief. > > Consider .. > > Scenario: > For whatever reason -- you want to restore the /etc directory from a > local backup. > Lets just use a simple example.. > > "cp" should handle this. > "rsync" should also should handle this. > > But "cp" is your friend if you make an error ... "rsync" is not. > > OK There is NO source or destinantion directory "ets" but you make a > typo "ets" instead of "etc" > > "cp" will give you an error message whereas "rsync" will do what is not > intended and you will be *unaware* > > So the following commands > > [r...@localhost ~]# cp -a/backup/etc/* /ets > > [r...@localhost ~]# rsync -a/backup/etc/* /ets > > > "cp" will error out telling you that the target is not a directory if you use cp -ar /backup/etc /etc, cp, won't give you a warning. > whereas > "rsync will SILENTLY create the dir (ets) and populate it. so add a "-v" and you'll see some output telling you "created directory ets". This is not unusual. Most unix commands only bother you when there's a problem, and there was no problem here. Of course, you're going to ignore that output anyway, aren't you... > > So if you didn't check the result disaster beckons. So check it. > > Note that the creation of directories occur without a trailing slash on the > source. > But in that instance directory created is the name of the source directory. Note that blindly using *any* command, without paying attention, without understanding what you're doing, can lead to disaster. This is a PEBKAC, not a fault of the tool. > > > I have found some other gotchas .. But do be aware of this (nasty) > feature. > Won't go into detail but some are . No, please do! > Like the deal with the trailing slash . which can cause issues --- > (often put there by bashs tab completion). > I like putting a "*" after a trailing slash as i find it more intuitive. > Also creating a new dir once -- but not twice.. > Blah..Blah > > Cheers > Roger > -- > SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ > Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html > -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
[SLUG] Just sharing a gotcha with "rsync" that caused me big trouble ...extra
Just sharing a gotcha with "rsync" that caused me big trouble ... what's nasty about rsync ?.. .. which may cause devastating consequences. rsync is in my opion the best thing since sliced bread... but be careful. CLI commands -- cp, rcp, scp, rsync, all have similarites BUT there are some nasty gotcha's when switching from one to another. You probably noticed some oddities , but had worked around it. (with the help of an error message) Without an error message you may had come to grief. Consider .. Scenario: For whatever reason -- you want to restore the /etc directory from a local backup. Lets just use a simple example.. "cp" should handle this. "rsync" should also should handle this. But "cp" is your friend if you make an error ... "rsync" is not. OK There is NO source or destinantion directory "ets" but you make a typo "ets" instead of "etc" "cp" will give you an error message whereas "rsync" will do what is not intended and you will be *unaware* So the following commands [r...@localhost ~]# cp -a/backup/etc/* /ets [r...@localhost ~]# rsync -a/backup/etc/* /ets "cp" will error out telling you that the target is not a directory whereas "rsync will SILENTLY create the dir (ets) and populate it. So if you didn't check the result disaster beckons. Note that the creation of directories occur without a trailing slash on the source. But in that instance directory created is the name of the source directory. I have found some other gotchas .. But do be aware of this (nasty) feature. Won't go into detail but some are . Like the deal with the trailing slash . which can cause issues --- (often put there by bashs tab completion). I like putting a "*" after a trailing slash as i find it more intuitive. Also creating a new dir once -- but not twice.. Blah..Blah Cheers Roger -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
