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If you have ever been trying to look for a list of processes based on their elapsed time you don't need to look any further.
This command lets you find the list of processes ordered in a reversed order (oldest at the top) that have been running for over an hour on your system. Any system processes are filtered out, leaving only user initiated ones in. I find it extremely useful for debugging and performance analysis.
Enable tracing and print a timestamp before the command to be invoked.
Original author: Peter Eisentraut
Sometimes it is necessary to view debug messages to troubleshoot any
SSH connection issues. pass -v (lowercase v) option to the ssh as shown
below to view the ssh debug messages.
Very useful for test a script. After launch this command, you only have to press ENTER for launch your script again. I work with screen and tape ENTER instead of '!!'+ENTER
If you break your script with CTRL-C, it will wait for press ENTER and will re-launch
You can write like it : while read -p "Press ENTER" ; do python ; done
If you need to xdebug a remote php application, which is behind a firewall, and you have an ssh daemon running on that machine. you can redirect port 9000 on that machine over to your local machine from which you run your xdebug client (I am using phpStorm)
So, run this command on your local machine and start your local xdebug client, to start debugging.
When debugging an ssh connection either to optimize your settings ie compression, ciphers, or more commonly for debugging an issue connecting, this alias comes in real handy as it's not easy to remember the '-o LogLevel=DEBUG3' argument, which adds a boost of debugging info not available with -vvv alone.
Especially useful are the FD info, and the setup negotiation to create a cleaner, faster connection.
Sometimes a program refuses to read a file and you're not sure why. You may have display_errors turned off for PHP or something. In this example, fopen('/var/www/test/foo.txt') was called but doesn't have read access to foo.txt.
Strace can tell you what went wrong. E.g., if php doesn't have read access to the file, strace will say "EACCESS (Permission denied)". Or, if the file path you gave doesn't exist, strace will say "ENOENT (No such file or directory)", etc.
This works for any program you can run from the command-line, e.g., strace python myapp.py -e open,access...
Note: the above command uses php-cli, not mod_php, which is a different SAPI with diff configs, etc.
Turn shell tracing and verbosity (set -xv) on/off in any Bourne-type shell
If either -x or -v is set, the function turns them both off.
If neither is on, both are turned on.
Running this command turns shell tracing and shell verbose debugging on or off. Not only does it do that, it also uses your terminals builtin method of setting colors to make debugging much easier.
It looks at the current shell options contained in the $- special bash variable and that lets this function set the opposite of the current value. So from the shell you could do a:
setx; echo "y" | ( cat -t ) | echo "d"; setx
and it will turn on debbuggin.
This is an amazingly useful function that is perfect to add system-wide by adding it to /etc/profile or /etc/bashrc.. You can run it from the shell, and you can also use it in your shell scripts like my .bash_profile - http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html
or you can add "-x" to get a typical hexdump like output
USAGE: gate listening_port host port
Creates listening socket and connects to remote device at host:port. It uses pipes for connection between two sockets. Traffic which goes through pipes is wrote to stdout. I use it for debug network scripts.