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 X11R4
head
HEAD(1) User Commands HEAD(1)NAME
head - output the first part of files
SYNOPSIS
head [OPTION]... [FILE]...
DESCRIPTION
Print the first 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=[-]NUM
print the first NUM bytes of each file; with the leading '-', print all but the last NUM bytes of each file
-n, --lines=[-]NUM
print the first NUM lines instead of the first 10; with the leading '-', print all but the last NUM lines of each file
-q, --quiet, --silent
never print headers giving file names
-v, --verbose
always print headers giving file names
-z, --zero-terminated
line delimiter is NUL, not newline
--help display this help and exit
--version
output version information and exit
NUM 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.
AUTHOR
Written by David MacKenzie and Jim Meyering.
REPORTING BUGS
GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
Report head translation bugs to <http://translationproject.org/team/>
COPYRIGHT
Copyright (C) 2017 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 tail(1)
Full documentation at: <http://www.gnu.org/software/coreutils/head>
or available locally via: info '(coreutils) head invocation'
GNU coreutils 8.28 January 2018 HEAD(1)