Commands using grep (1,935)

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Print all /etc/passwd lines with duplicated uid
Prints all the lines in /etc/passwd belonging to users with a duplicated uid. It also adds the hostname to the beginning of the line. It's been tested in AIX, Solaris and Linux.

Protect directory from an overzealous rm -rf *
-R Recursively change attributes of directories and their contents. +i to set the immutable bit to prevent even root from erasing or changing the contents of a file.

find the longest command in your history

View a man page on a nice interface
A great way of viewing some man page while using gnome.

List open TCP/UDP ports

back ssh from firewalled hosts
host B (you) redirects a modem port (62220) to his local ssh. host A is a remote machine (the ones that issues the ssh cmd). once connected port 5497 is in listening mode on host B. host B just do a ssh 127.0.0.1 -p 5497 -l user and reaches the remote host'ssh. This can be used also for vnc and so on.

Python version 3: Serve current directory tree at http://$HOSTNAME:8000/
In Python version 3, the module was merged into http.server. Gentlemen, change your aliases.

View a sopcast stream
Get sopcast links for live sports from http://myp2p.eu (for example) Get sp-sc or sp-auth binary by googling (sopcast + linux) eg http://www.jbg.f2s.com/sp-sc.gz Requires the 32bit libstdc++5 package. After exiting mplayer, type 'killall sp-sc'

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Set file access control lists
The file myfile is owned by tom and has read and write permissions for tom. Group and other permissions are empty which make myfile readable and writable only by tom. setfacl enables user tom to give read permission to user john only. The command 'ls -l' shows a '+' sign telling us that file access control list has been setup for myfile.


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