SysAdmin Valley

Here’s another useful what to query RPM’s installed on your machine. I had the need to see not only the rpm’s installed on the machine but what the size of each package was, so here’s the query I used

rpm -qa --queryformat='%{SIZE} %{NAME}-%{VERSION}-%{ARCH}\n'

You can then sort the output based on size

rpm -qa --queryformat='%{SIZE} %{NAME}-%{VERSION}-%{ARCH}\n' | sort -n

Now that 64bit systems have come along, I’ve come across issues using just

rpm -qa

If you have package that installs both a x86 & x86_64 package, it will only show the package name once for both packages.

Try the following, it will list all packages along with the arch type

rpm -qa --queryformat "%{NAME}-%{VERSION}.%{ARCH}\n"

Say in the past you had run a very long command, if you want to re-run the last “whatever” command type

!whatever

If you want to re-run the last command but substitute v3 for v4 run:

^v3^v4

Easy to use way to search and replace in VI.

1. Open your file: vi filename
2. type: :0,$s/search_term/replace_term/g

This will replace all search_term with replace_term from the beginning (0) to the end ($) of the file. You can also use (.) which means from “here”, so (.,$) would be here to the end. (0,.) would be beginning to here.

You can also use (%) instead of (0,$) to search entire document. Or you can use (23,90) to only search between lines 23 and 90 (substitute your own line numbers).

If you want to kill a process, but don’t know the process id, but you do know the service name, try this. It will get the process id and kill it all in one step.  Replace httpd with the process name you want to kill

ps auxwww | grep httpd | awk ‘{print $2}’ | xargs kill -15

I needed a quick command to delete a specific file or directory that existing in multiple subdirectories. Here is what I came up with.

find . -name “filename” | xargs rm -rf

Note: files can be a filename or directory name. You can use rm with -rf or without

Here are a few tips on how to get around in NANO

To edit a file type: nano filename
*** if you are using one of the legacy Linux servers, it will say NANO Command Not Found. Use PICO instead

• CTRL-Y – Page Up
• CTRL-V – Page Down
• CTRL-W – Where Is (Search)
• CTRL-K – Cut current line (press multiple times to multiple lines)
• CTRL-U – Paste lines just cut (if you cut multiple lines it will paste them all)
• CTRL-C – Word Count / Line Count / Current Position (will be displayed at bottom of page)
• CTRL-O then ENTER – Save file

• If no changes have been made, you can exit by hitting CTRL-X
• If changes have been made, but you DO NOT want to save, hit CTRL-X then N
• If changes have been made, but you DO WANT to save, hit CTRL-X then Y, then ENTER

Here are a few tips on how to get around in VI

To edit a file type: vi filename

Basic vi commands

• i – Change to insert mode (edit mode)
• CTRL-C – Change to command mode (exit edit mode)
• :w – Save the file being edited (command mode only)
• :wq – Save file and Quit (command mode only)
• :q – Quit (command mode only)
• :q! – Quit without saving (command mode only)
• h/j/k/l Navigation keys if your arrows break (command mode only) (Try pressing scroll-lock first to try and make arrows work)