Jayant Verma

Finding files associated with a Linux command means knowing what kinds of files to look for. The whereis command searches its configured locations for files associated with a command. This article explains how to read whereis results and narrow a lookup by file category or directory. TL;DR The whereis command searches for a command’s executable,

Before using a relative filename in a Linux shell, it helps to know which directory the shell is working in. The pwd command prints the path of that directory. This article shows how to use pwd to check the current directory and choose whether to read its logical or physical path. TL;DR The pwd command

To inspect one running program, you first need to pick it out of the process list. The ps command prints a point-in-time listing of selected processes and their attributes. I’ll explain what ps shows and show how to find a process by ID or executable name. TL;DR: The ps command in Linux Use ps to

Setting up Java on Linux means choosing the installation directory a program should use. JAVA_HOME is an environment variable that names that Java installation directory. I’ll show you how to find the JDK root and set JAVA_HOME for the shell or system that runs your program. TL;DR: Set JAVA_HOME to the JDK directory Set JAVA_HOME

Working with text records at the shell can mean finding the rows and fields that matter. awk reads text records and lets you select fields or calculate totals. I’ll show how to select fields and summarize matching records, then save the program in an awk file for reuse. TL;DR: Use awk to select and reshape

To see which login sessions a Linux system has recorded, use the who command. It reads login records, usually from utmp, and lists the sessions they contain. I’ll explain its output fields and show how to select the session associated with standard input. TL;DR The who command lists login sessions recorded on a Linux system,

Terminal output can be useful to review alongside the commands that produced it. The Linux script command records an interactive terminal session in a file called a typescript, which contains entered commands and visible results. I’ll show you how to record and replay a session, and how to check its log for private input. TL;DR:

To schedule a Linux command for one future run, use at. The at utility queues a shell command as a job for the atd scheduler service to run once at a later time. I’ll explain what at does and show how to schedule a one-time job. TL;DR: Schedule a one-time Linux command The at command

A Linux machine can show little free RAM when you are checking whether another application has room to run. Linux memory management assigns physical pages to processes and cached file data as demand changes. This article shows how to compare MemFree with MemAvailable and use vmstat to check for active paging. TL;DR: Read Available Memory

A Linux account may need access to a shared directory or device that is controlled by a group. The usermod command adds an existing account to a supplementary group, an additional membership that does not change its primary group. I’ll show how to add an account to one or more groups and check its membership