The sar utility is part of the sysstat monitoring tools. sar collects a huge amount system activity data. This includes data about CPU and memory…
Category: Linux command line
Inspecting processes with top
The top utility is useful if you want to monitor system performance over time. Whereas ps gives you a static overview of processes – it…
Inspecting processes using ps
The ps utility displays information about processes. The information shown is similar to the output in the “fields display” of top. The main difference is…
Checking memory usage with free
The free utility shows the amount of free and used memory in a system. The output is similar to the memory information displayed by top.
Getting file information using stat
The stat utility prints information about files. You are mostly likely to use it when you want to know when a file was last changed,…
The PATH variable
Linux systems use lots of environment variables. Among others, there are variables that store your username ($USER) and the current directory ($PWD). One of the…
Standard file streams
On Unix-like systems, file streams are used to redirect input or output. If you have spent some time on the command line then you have…
SSL Labs on the command line
In our article about checking the health of SSL certificates we used Qualys’ online SSL Labs checker. If you prefer the command line and know…
Checking disk space usage with du
The du utility is used to estimate disk space usage. Its syntax is: