Some additional command-line tools that I use to install and use on my client Systems
To stress a Web Server
discard unused blocks on a mounted filesystem (local or remote). Is useful for freeing blocks no longer used in ZFS zvols. That can also be achieved by mount -o discard
An improved top
To set the metrics of all IPV4 routes attached to a given network interface
To watch metrics for a network interface (or wireless)
CPU and IO devices stats. I modified some collectors for telegraf and influxdb consumed by grafana for fetching the Write KB/s, Read KB/s, Bandwidth of the Magnetic Spinning drives and SSD during declustered rebuild.
Perform network throughput tests
java (jre Oracle and OpenJDK)
To see in real time queries and slow queries to mysql
Show the space used by any directory and subdirectory
nginx (fpm-php) and apache
Offers monitoring of different aspects: Network, Disk, Processes…
perf stat ls
PHP + curl + mysql (hhvm)
python-pip and pypy
Utility for dealing with the S.M.A.R.T. features of the disks, knowing errors…
A poor’s man VPN through SSH that is available for Linux and Mac OS X.
E.g.: sudo sshuttle -r email@example.com:8275 172.30.0.0/16
Sshuttle forwards TCP and DNS but does not forward UDP or ICMP. So ping or ipmi protocol won’t work. But it does work for http, https, ssh…
To trace the system calls and signals.
To redirect the output to another process use:
strace zpool status 2>&1 | less
(systemd-cgtop for RHEL)
To see the traffic to your NIC
Sergey Davidoff stumbled upon a project called compcache that creates a RAM based block device which acts as a swap disk, but is compressed and stored in memory instead of swap disk (which is slow), allowing very fast I/O and increasing the amount of memory available before the system starts swapping to disk. compcache was later re-written under the name zRam and is now integrated into the Linux kernel.