rpm automatically place a new installed kernel as the first option. However, I want to move it as the last one - to end of the file.
Grub configuration file looks like this:
default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title Fedora (2.6.29.6-217.2.7.fc11.x86_64)
root (hd0,0)
kernel /vmlinuz-2.6.29.6-217.2.7.fc11.x86_64 ro root=/dev/mapper/main-root rhgb quiet
initrd /initrd-2.6.29.6-217.2.7.fc11.x86_64.img
title Fedora (2.6.29.6-217.2.3.fc11.x86_64)
root (hd0,0)
kernel /vmlinuz-2.6.29.6-217.2.3.fc11.x86_64 ro root=/dev/mapper/main-root rhgb quiet
initrd /initrd-2.6.29.6-217.2.3.fc11.x86_64.img
title Fedora (2.6.29.6-213.fc11.x86_64)
root (hd0,0)
kernel /vmlinuz-2.6.29.6-213.fc11.x86_64 ro root=/dev/mapper/main-root rhgb quiet
initrd /initrd-2.6.29.6-213.fc11.x86_64.img
My goal is to move first option (217.2.3) to end. Now I figure out how to delete it:
sed -e '/(2.6.29.6-217.2.7.fc11.x86_64)/,+3d' /boot/grub/menu.lst
p command only prints current line (not as in vim, where it means paste).
Do you have any ideas how to automatically move this part of file to its end?
I have to answer myself. :-)
sed '/\(2.6.18-157.el5\)/,+4 { H; d; }; $ { p; x; }' /boot/grub/menu.lst
If you are not fluent with sed (me neither), there is more verbose version
sed '
/\(2.6.18-157.el5\)/,+3 { #Find line which contains version of our kernel in parentheses and took also 3 following lines
H # Append this line into buffer
d # Delete line
}
$ { # On the last line
p # Print current line
x # Change current line with buffer and vice versa
# Afterwards sed print current line => in our case deleted line
}' /boot/grub/menu.lst
A very similar task was covered extensively here
Yes, there is some satisfaction in a well crafted sed command, but I think I would tend to use an editor, so I could see the lines I was going to move around, and not have to worry about getting the line numbers wrong in a command.
Related
The vim manual page contains two similar -r type commands. I'll give more background below, this question is really how to invoke the first type of -r to list the swap files, but avoid the second -r that invokes recovery
-r List swap files, with information about using them for re‐
covery.
-r {file} Recovery mode. The swap file is used to recover a crashed
editing session. The swap file is a file with the same
filename as the text file with ".swp" appended. See ":help
recovery".
The -r without filename (the first -r above ) reports on the swap files of other files too, including ones in other directories
Background:
I'm trying to have vim report the swap files of a specific file (mostly to determine if vim still editing the file). If the file is being edited ( in another window, either on linux or cygwin ) I can 'raise' that window up to the top with "\e[2t\e[1t" as I have successfully be able to do thanks to Bring Window to Front
Vim has multiple swap file names, and multiple directories that it could put a file, so I want to ask vim, please tell me the name of the swap files that are currently in use for a given file, and if there is a current vim process on the file. Unfortunately, sometimes vim will open a command file in recovery mode in unexpected ways.
I'm invoking vim like this vim -r -c :q file, well actually, I'm invoking it from script, since I want vim to see something more like a terminal, then I look at the output file, so it's more like script -q -c "vim -r -c :q foo" fooscript, then I look in the fooscript file for messages like /Note: process STILL RUNNING: (\d+)/
It is beginning to look like I need to use vim -r without a file name, and parse the output of the -r report, and that there isn't a way to get the report pre-filtered to a single file in question.
after switching my focus to just vim -r, and
Knowing that vim will try to put the swap file into the same directory as the file it's editing ( thanks to #romainl for the pointer to :help swap-file )
observing that vim -r reports on the files in the current directory first,
observing that the file name associated with the swap file is reported before the process id of the vim process, and
observing that vim appends (STILL RUNNING) if it finds the active process
I changed the current directory appropriately and ran this code after plugging in the name of the file-to-search-for
perl -lne '
last if /^\s+In directory/;
undef $f if /^\d+/;
$f = $1 if /^\s+file name:\s+(.*)\s*$/;
if ( $f =~ m#/file-to-search-for# && /^\s+ process ID:\s(\d+).*?STILL RUNNING/ ) {
print $1;
$pid //= $1;
}
END { exit !$pid; } '
The pid of the running vim process is printed, and the exit status is zero when the appropiate swap file is found, and non-zero if the file was not being edited
sed -i '/#if UTS_UBUNTU_RELEASE_ABI > 255/c\/*#if UTS_UBUNTU_RELEASE_ABI > 255' /usr/src/ixgbevf-2.16.4/src/kcompat.h
I am trying to understand the above command but couldn't figure out what c\ is doing here?
This sed command says to test lines for the regular expression #if UTS_UBUNTU_RELEASE_ABI > 255 (because it starts with forward slash), if so, use the change command to replace the whole line with whatever follows. (the -i means in place.)
In this case, it will change the matching line to be the beginning of a block comment (inserts /*) per my local testing.
how to use "grep" command to find a match and to print followup of 10 lines from the match. this i need to get some error statements from log files. (else need to download use match for log time and then copy the content). Instead of downloading bulk size files i need to run a command to get those number of lines.
A default install of Solaris 10 or 11 will have the /usr/sfw/bin file tree. Gnu grep - /usr/sfw/bin/ggrep is there. ggrep supports /usr/sfw/bin/ggrep -A 10 [pattern] [file] which does what you want.
Solaris 9 and older may not have it. Or your system may not have been a default install. Check.
Suppose, you have a file /etc/passwd and want to filter user "chetan"
Please try below command:
cat /etc/passwd | /usr/sfw/bin/ggrep -A 2 'chetan'
It will print the line with letter "chetan" and the next two lines as well.
-- Tested in Solaris 10 --
I need to make a change in the php.ini configuration file via sed (or similar).
I need to add the following text:
extension=solr.so
The line has to be added as line number 941 in the configuration file. However, if the file is already there, it should not be added again.
I guess there are two approaches: 1) replace line 941 with the text, or 2) search for the text and add it to line 941 if there are not matches.
I have the following command that works fine, except that the line is added again if the script is run again:
sed '941i\
extension=solr.so' /etc/php5/apache2/php.ini > /etc/php5/apache2/php.ini
How can I make sure that this command does not add the line if it is already there?
The easiest way would be to test before using grep, for example:
grep -q -e 'extension=solr.so' file || sed '...'
Also, it is estrange that you need exactly that line. You should add it at the end, or something like that.
Also, note that taking the same file as input and output never should be done. This can damage the file badly. You should be using the -i sed parameter to do in-place editing.
The file is initially
$cat so/app.yaml
application: SO
...
I run the following command. I get an empty file.
$sed s/SO/so/ so/app.yaml > so/app.yaml
$cat so/app.yaml
$
How can you use SED to edit the file and not giving me an empty file?
$ sed -i -e's/SO/so/' so/app.yaml
The -i means in-place.
The > used in piping will open the output file when the pipes are all set up, i.e. before command execution. Thus, the input file is truncated prior to sed executing. This is a problem with all shell redirection, not just with sed.
Sheldon Young's answer shows how to use in-place editing.
You are using the wrong tool for the job. sed is a stream editor (that's why it's called sed), so it's for in-flight editing of streams in a pipe. ed OTOH is a file editor, which can do everything sed can do, except it works on files instead of streams. (Actually, it's the other way round: ed is the original utility and sed is a clone that avoids having to create temporary files for streams.)
ed works very much like sed (because sed is just a clone), but with one important difference: you can move around in files, but you can't move around in streams. So, all commands in ed take an address parameter that tells ed, where in the file to apply the command. In your case, you want to apply the command everywhere in the file, so the address parameter is just , because a,b means "from line a to line b" and the default for a is 1 (beginning-of-file) and the default for b is $ (end-of-file), so leaving them both out means "from beginning-of-file to end-of-file". Then comes the s (for substitute) and the rest looks much like sed.
So, your sed command s/SO/so/ turns into the ed command ,s/SO/so/.
And, again because ed is a file editor, and more precisely, an interactive file editor, we also need to write (w) the file and quit (q) the editor.
This is how it looks in its entirety:
ed -- so/app.yaml <<-HERE
,s/SO/so/
w
q
HERE
See also my answer to a similar question.
What happens in your case, is that executing a pipeline is a two-stage process: first construct the pipeline, then run it. > means "open the file, truncate it, and connect it to filedescriptor 1 (stdout)". Only then is the pipe actually run, i.e. sed is executed, but at this time, the file has already been truncated.
Some versions of sed also have a -i parameter for in-place editing of files, that makes sed behave a little more like ed, but using that is not advisable: first of all, it doesn't support all the features of ed, but more importantly, it is a non-standardized proprietary extension of GNU sed that doesn't work on many non-GNU systems. It's been a while since I used a non-GNU system, but last I used one, neither Solaris nor OpenBSD nor HP-UX nor IBM AIX sed supported the -i parameter.
I believe that redirecting output into the same file you are editing is causing your problem.
You need redirect standard output to some temporary file and when sed is done overwrite the original file by the temporary one.