Modern shells can hold data in memory by using variables. Here's an example:
producing:
So this holds the last 3 lines of Lincoln's Gettysburg address in memory, variable v1 , then removes the file, and finally writes the saved data to the file. One could also just truncate the file if one wanted to keep the inode.
This obviously has risks -- if the code is wrong or if something else bad happens, it's possible that the entire file could be lost. Of course, one has backups for such occasions.
This method works in the versions of Linux and bash as noted. Will it work in your system? I don't know, but you could test it, and, as usual, be prepared with a backup if things go awry.
Hi,
There seems to some hack attempts in my site. I have attached the index page of my site and I need to remove the below lines from the index page. The below lines are at the center of the file.
-->
</style>
<script>E V A L( unescape(... (5 Replies)
All,
I have a text file with several entries like below:
personname
personname.domain.com
I know there is a way to use vi to remove only the personname.domain.com line. Can someone help? I believe that it involves /s/g/ something...I just can't remember the exact syntax.
Thanks (2 Replies)
Hi gurus,
i'm trying to remove a number of lines from a large file using the following command:
sed '1,5000d' oldfile > newfile
Somehow the lines in the old file are not deleted...
Am I doing this wrongly? Any suggestions? :confused:
Thanks! :)
wee (10 Replies)
A small question
I have a test.txt file
I have contents as:
a:google
b:yahoo
:
c:facebook
:
d:hotmail
How do I remove the line with :
my output should be
a:google
b:yahoo
c:facebook
d:hotmail (5 Replies)
Hi,
I'm not a expert in shell programming, so i've come here to take help from u gurus.
I'm trying to tailor a csv file that i got to make it work for the LOAD FROM command.
I've a datatable csv of the below format -
--in file format
xx,xx,xx ,xx , , , , ,,xx,
xxxx,, ,, xxx,... (11 Replies)
Hey Gang-
I have a list of servers. I want to exclude servers that begin with and end with certain characters. Is there an easy command to do this?
Example
wvm1234dev
wvm1234pro
uvm1122dev
uvm1122bku
uvm1344dev
I want to exclude any lines that start with "wvm" OR "uvm" AND end... (7 Replies)
I have two files, a keepout.txt and a database.csv. They're unsorted, but could be sorted.
keepout:
user1
buser3
anuser19
notheruser27
database:
user1,2343,"information about",field,blah,34
user2,4231,"mo info",etc,stuff,43
notheruser27,4344,"hiya",thing,more thing,423... (4 Replies)
Hello everyone,
Although it seems easy, I've been stuck with this problem for a moment now and I can't figure out a way to get it done.
My problem is the following:
I have a file where each line is a sequence of IP addresses, example :
10.0.0.1 10.0.0.2
10.0.0.5 10.0.0.1 10.0.0.2... (5 Replies)
I have been searching and trying to come up with an awk that will perform the following on a
converted text file (original is a pdf).
1. Since the first two lines are (begin with) text they are removed
2. if $1 is a number then all text is merged (combined) into one line until the next... (3 Replies)
Discussion started by: cmccabe
3 Replies
LEARN ABOUT SUSE
tail
TAIL(1) User Commands TAIL(1)NAME
tail - output the last part of files
SYNOPSIS
tail [OPTION]... [FILE]...
DESCRIPTION
Print the last 10 lines of each FILE to standard output. With more than one FILE, precede each with a header giving the file name. With
no FILE, or when FILE is -, read standard input.
Mandatory arguments to long options are mandatory for short options too.
-c, --bytes=N
output the last N bytes; alternatively, use +N to output bytes starting with the Nth of each file
-f, --follow[={name|descriptor}]
output appended data as the file grows; -f, --follow, and --follow=descriptor are equivalent
-F same as --follow=name --retry
-n, --lines=N
output the last N lines, instead of the last 10; or use +N to output lines starting with the Nth
--max-unchanged-stats=N
with --follow=name, reopen a FILE which has not changed size after N (default 5) iterations to see if it has been unlinked or
renamed (this is the usual case of rotated log files)
--pid=PID
with -f, terminate after process ID, PID dies
-q, --quiet, --silent
never output headers giving file names
--retry
keep trying to open a file even when it is or becomes inaccessible; useful when following by name, i.e., with --follow=name
-s, --sleep-interval=S
with -f, sleep for approximately S seconds (default 1.0) between iterations
-v, --verbose
always output headers giving file names
--help display this help and exit
--version
output version information and exit
If the first character of N (the number of bytes or lines) is a `+', print beginning with the Nth item from the start of each file, other-
wise, print the last N items in the file. N may have a multiplier suffix: b 512, kB 1000, K 1024, MB 1000*1000, M 1024*1024, GB
1000*1000*1000, G 1024*1024*1024, and so on for T, P, E, Z, Y.
With --follow (-f), tail defaults to following the file descriptor, which means that even if a tail'ed file is renamed, tail will continue
to track its end. This default behavior is not desirable when you really want to track the actual name of the file, not the file descrip-
tor (e.g., log rotation). Use --follow=name in that case. That causes tail to track the named file by reopening it periodically to see if
it has been removed and recreated by some other program.
AUTHOR
Written by Paul Rubin, David MacKenzie, Ian Lance Taylor, and Jim Meyering.
REPORTING BUGS
Report tail bugs to bug-coreutils@gnu.org
GNU coreutils home page: <http://www.gnu.org/software/coreutils/>
General help using GNU software: <http://www.gnu.org/gethelp/>
COPYRIGHT
Copyright (C) 2009 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.
SEE ALSO
The full documentation for tail is maintained as a Texinfo manual. If the info and tail programs are properly installed at your site, the
command
info coreutils 'tail invocation'
should give you access to the complete manual.
GNU coreutils 7.1 July 2010 TAIL(1)