I forgot to stop a TV recording, which resulted in a giant file taking up all remaining free space on disk.
Now I want to keep only the first 12GB from this file.
The disk is so full I can't free 12GB on it, to be able to use the "head" command.
I know I can (and will) use something like "head --bytes=12000m FILE | ssh remoteuser@remotehost 'cat >TAIL-FILE'". But…
I'd like to know how I can truncate a file to its first bytes when neither the network nor extra disk space is available.
Yves.
Full Version: Shell command to truncate a file [solved]
a quick search for linux and truncate revealed this links: http://linux.about.com/library/cmd/blcmdl2_truncate.htm
which according to pbone.net is either in the ltp package: http://rpm.pbone.net/index.php3/stat/4/idp...0.i386.rpm.html
or in the embutils package: http://rpm.pbone.net/index.php3/stat/4/idp...1.i586.rpm.html
based on the description it does not move the file so it seems like what you are looking for.
ciao!
which according to pbone.net is either in the ltp package: http://rpm.pbone.net/index.php3/stat/4/idp...0.i386.rpm.html
or in the embutils package: http://rpm.pbone.net/index.php3/stat/4/idp...1.i586.rpm.html
based on the description it does not move the file so it seems like what you are looking for.
ciao!
QUOTE (ramfree17 @ Jun 3 2008, 05:25 AM) 
a quick search for linux and truncate revealed this links: http://linux.about.com/library/cmd/blcmdl2_truncate.htm
This is a C system call. I cannot use it directly.
QUOTE
which according to pbone.net is either in the ltp package: http://rpm.pbone.net/index.php3/stat/4/idp...0.i386.rpm.html
And those are just test cases for the kernel function that is called by the above system call.
QUOTE
or in the embutils package: http://rpm.pbone.net/index.php3/stat/4/idp...1.i586.rpm.html
based on the description it does not move the file so it seems like what you are looking for.
based on the description it does not move the file so it seems like what you are looking for.
I didn't notice this one before. It may indeed be what I'm looking for, even though it's deep under /usr/lib… Thanks, I'll try.
Yves.
Excellent! 
It works:
Thanks again.
Yves.
It works:CODE
[yves@localhost ~]$ truncate
usage: truncate size filename [filename...]
[yves@localhost ~]$ echo "hello hello" >testfile
[yves@localhost ~]$ echo "bye bye" >>testfile
[yves@localhost ~]$ ls -li testfile
711918 -rw-r--r-- 1 yves yves 20 2008-06-03 10:27 testfile
[yves@localhost ~]$ cat testfile
hello hello
bye bye
[yves@localhost ~]$ truncate 10 testfile
[yves@localhost ~]$ ls -li testfile
711918 -rw-r--r-- 1 yves yves 10 2008-06-03 10:27 testfile
[yves@localhost ~]$ cat testfile
hello hell[yves@localhost ~]$
usage: truncate size filename [filename...]
[yves@localhost ~]$ echo "hello hello" >testfile
[yves@localhost ~]$ echo "bye bye" >>testfile
[yves@localhost ~]$ ls -li testfile
711918 -rw-r--r-- 1 yves yves 20 2008-06-03 10:27 testfile
[yves@localhost ~]$ cat testfile
hello hello
bye bye
[yves@localhost ~]$ truncate 10 testfile
[yves@localhost ~]$ ls -li testfile
711918 -rw-r--r-- 1 yves yves 10 2008-06-03 10:27 testfile
[yves@localhost ~]$ cat testfile
hello hell[yves@localhost ~]$
Thanks again.
Yves.
cool!
ciao!
ciao!
If you are using bash you can simply do:
> filename
not sure about other shells...
> filename
not sure about other shells...
QUOTE (senyahnoj @ Oct 23 2008, 03:23 PM)
If you are using bash you can simply do:
> filename
> filename
wouldnt that overwrite the whole file (aka redirection)? the original problem is to truncate a file up to a certain point so that the file contents is still usable and space is freed up.
ciao!
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