Practice the core utility commands you reach for daily as a sysadmin: time, uptime, identity, kernel details, calendars, and quick math. Build speed and confidence by validating outputs and knowing what each tool proves about the system.
A teammate needs quick verification for an incident note: current time, uptime, which host they are on, kernel details for compatibility context, and a simple calculation without leaving the terminal. Your task is to run the correct commands, interpret outputs, and capture evidence reliably.
These commands are the first 60 seconds of most troubleshooting sessions. They establish baseline context before you chase symptoms.
bc to evaluate a simple arithmetic expression.date
Use date to confirm the system clock for logs, tickets, cron schedules, and incident timelines.
If timestamps do not line up, you can misread the entire sequence of events.
Wed Oct 1 14:32:08 EDT 2025uptime
uptime shows how long the system has been running and reports load averages. This is quick evidence
for restarts, stability, and whether the box is likely overloaded.
14:32:10 up 3 days, 4:28, 2 users, load average: 0.48, 0.52, 0.47hostnameThis confirms which system you are actually on. In real environments, it is common to have multiple terminals, jump hosts, and similarly named servers.
lab-serveruname -a
uname -a provides kernel version and architecture context. Capture this early before you diagnose
driver issues, compatibility problems, or kernel-specific behavior.
Linux lab-server 5.15.0-89-generic #99-Ubuntu SMP Fri Sep 6 12:34:56 UTC 2025 x86_64 GNU/Linuxcal
Use cal for quick scheduling context. This is useful when you are coordinating maintenance windows,
deadlines, and on-call handoffs.
October 2025
Su Mo Tu We Th Fr Sa
1 2 3 4
5 6 7 8 9 10 11
12 13 14 15 16 17 18
19 20 21 22 23 24 25
26 27 28 29 30 31(8 + 2) * 5 using bc.
echo '(8 + 2) * 5' | bc
bc is a CLI calculator. Use it for quick arithmetic when you are sizing storage, estimating time
windows, or validating simple math without leaving the terminal.
50
If date is incorrect, incident timelines and log correlation become unreliable. Capture the output
as evidence and escalate clock/time sync issues before trusting timestamps.
Load averages are a signal, not a diagnosis. Treat them as a prompt to investigate CPU pressure, blocked I/O, or runaway processes after you capture baseline evidence.
If hostname is not the system you intended, stop. Troubleshooting the wrong machine is a common
operational failure mode.
If bc is missing or returns a parse error, confirm package availability and re-check the expression
formatting. Treat this as a toolchain issue, not a math issue.
This lab is read-only and does not change system state. Your cleanup is simply to confirm the commands produced the expected evidence and that you captured outputs you would place into a ticket.
date
uptime
hostname
uname -a
cal
echo '(8 + 2) * 5' | bcYou can reproduce the same baseline context on demand and explain what each output proves about the system.
date : Prints the current system date and time.
uptime : Shows how long the system has been running and the load averages.
hostname : Prints the system hostname.
uname -a : Displays kernel version and architecture information.
-a : Prints all available system information fields.cal : Prints a calendar for the current month.
echo '(EXPR)' | bc : Evaluates an arithmetic expression using bc.
| : Pipes output from echo into bc for evaluation.