ALA Post-Test Review | Advanced Linux Administration

1. Viewing & inspecting files

Read parts of a file without opening the whole thing — essential for large logs.

headfirst lines of a file (default 10)

head server_log.txt # first 10 lines head -n 20 server_log.txt # first 20 lines

Q1: use head to assess the start of a large log. cat dumps the whole file, tail shows the end, more scrolls but does not limit to the first 10.

taillast lines; tail -f follows live

tail -f /var/log/syslog # watch new lines as they arrive

2. Files & directories

Create, copy, and archive files and whole directory trees.

mkdircreate a directory

mkdir /path/to/project_docs mkdir -p a/b/c # create parent dirs as needed

Q4: mkdir creates the new directory in the specified location.

touchcreate an empty file / update timestamp

touch /home/user/config.txt

Q5: touch creates the file if it does not exist, and updates the timestamp if it does.

cp -rcopy a directory recursively

cp -r /src/dir /dest/dir # include all files + subdirectories

Q3: -r (recursive) copies the entire tree, preserving files and subdirectories.

tararchive container format (.tar)

tar -czf backup.tar.gz /src # create gzip archive tar -xzf backup.tar.gz # extract

Q13: tar bundles files and directory structures into one archive; convention is the .tar extension.

rsynccopy/sync directories across a network

rsync -av /src/ user@host:/dest/ # mirror over SSH, only changes

Q23: rsync is intended to copy complete directories across a network to another computer (efficiently, transferring only differences).

3. Ownership & permissions

Control who owns a file and what they may do with it.

chown user:groupchange owner and group

chown john:staff /path/to/file

Q2: chown john:staff sets user john and group staff. chmod changes permissions not ownership; chgrp changes only the group; setfacl changes the ACL, not ownership.

sticky bitrestrict deletion in shared dirs

chmod +t /shared # or chmod 1777 /shared ls -ld /tmp # drwxrwxrwt (the 't')

Q11: the sticky bit on a shared directory (like /tmp) prevents users from deleting each other's files — only the owner (or root) can delete a file.

ACLs — setfacl / getfaclper-user / per-group permissions

setfacl -m u:john:rw file # grant john read+write getfacl file # view the ACL

Q25: setfacl changes a file's ACL. Q12: a minimum ACL contains just the entries for owner, owning group, and other (the conventional permission bits); an extended ACL adds named users/groups plus a mask.

4. Shell & scripting

Bash basics tested on the exam.

letinteger arithmetic in Bash

let result=4+5 # result = 9 let "count += 1"

Q14: let performs an arithmetic operation in Bash (equivalent to $(( ))).

# commenta comment in a shell script

# this line is a comment, ignored by the shell

Q22: a comment is introduced with the # character. (Note: # at the end of a prompt also signals a root shell.)

Ctrl-Cinterrupt a running command

ping example.com # press Ctrl-C to stop

Q8: ping keeps sending packets until terminated by Ctrl-C (SIGINT).

5. Networking & DNS

Bring interfaces up, query DNS, and configure name resolution.

ip link set <dev> upenable a network interface

ip link set eth0 up # bring eth0 up ip link set eth0 down # take it down

Q7: ip link set eth0 up enables the device (the modern replacement for ifconfig eth0 up).

ping -woverall deadline in seconds

ping -w 10 example.com # exit after 10s regardless of packets

Q9: ping -w maxwait sets a timeout/deadline in seconds after which ping exits, regardless of packets sent or received. (Contrast -c = packet count.)

MX recordmail server for a domain

example.com. IN MX 10 mail.example.com.

Q10: an MX (Mail eXchanger) entry in the DNS zone file defines the mail server for a domain (forward resolution).

/etc/resolv.confDNS resolver configuration

nameserver 8.8.8.8 search example.com

Q24: name resolution (which DNS servers the host queries) is configured in /etc/resolv.conf.

6. Storage & system status

Mounts, swap, and load.

/etc/fstabfilesystems mounted at boot

/dev/sda2 none swap sw 0 0 UUID=... / ext4 defaults 0 1

Q19: every swap partition (and every persistent mount) has an entry in /etc/fstab.

swap partitiondisk-backed virtual memory

swapon --show free -h # see swap usage

Q20: the swap partition frees physical memory by copying temporarily unused memory pages to disk.

uptimeload average over 1/5/15 min

uptime # 14:22 up 3 days, load average: 0.15, 0.21, 0.18

Q21: uptime displays the system load over the last 1, 5, and 15 minutes.

7. Software & builds

Package relationships and building from source.

dependenciespackages / targets a thing needs

target: dependency1 dependency2 command-to-build-target

Q15: every Makefile rule consists of targets, their dependencies (prerequisites that must exist/build first), and the commands that build the target. Package managers resolve software dependencies the same way.

8. Boot & servicesLEGACY

Two items here use older installer / SUSE conventions. Know the exam answer, and the modern equivalent.

Boot from Hard Diskinstaller boot-menu option

Q6: on the installation boot menu, Boot from Hard Disk boots the OS already installed on disk (instead of starting the installer).

chkconfig apache2 offremove a service from the init process

chkconfig apache2 off # SysV: stop apache2 starting at boot

Q17: chkconfig apache2 off removes the apache2 service from the init (boot) process. The distractors (top, vmstat, iostat) are monitoring tools, not service managers.

Legacy → modern: on systemd use systemctl disable apache2 (stop it starting at boot) and systemctl stop apache2 (stop it now).

rcapache2 stopstop Apache (SUSE init script)

rcapache2 stop # SUSE rc-script form

Q18: the exam answer is rcapache2 stop, a SUSE rc service wrapper.

Legacy → modern: on current systemd systems use systemctl stop apache2 (or httpd on RHEL). Enable/disable at boot with systemctl enable/disable (replaces the old chkconfig).

9. Network monitoringLEGACY

Traffic-visanalyze connections to hosts

Q16: the exam answer is Traffic-vis, an older program that analyzes network connections to specific hosts.

Legacy → modern: for live per-connection traffic today use iftop, nload, bmon, or ss -tup / nethogs.

Answer index — all 25 questions (test order)

The correct answer for every question, with a one-line why and the topic it maps to.

Q	Tests	Answer	Why
Q1	View start of a log	`head`	First 10 lines; cat=all, tail=end, more=scroll.
Q2	Change owner+group	`chown john:staff`	chmod=perms, chgrp=group only, setfacl=ACL.
Q3	Copy a directory tree	`cp -r`	Recursive; preserves all files + subdirs.
Q4	Make a directory	`mkdir`	Creates the directory in the given location.
Q5	Create empty file	`touch`	Creates if absent; updates timestamp if present.
Q6	Installer boot menu [legacy]	`Boot from Hard Disk`	Boots the OS already installed on disk.
Q7	Enable an interface	`ip link set eth0 up`	Modern replacement for ifconfig up.
Q8	Stop ping	`Ctrl-C`	Sends SIGINT to terminate.
Q9	Ping deadline	`ping -w maxwait`	Exit after N seconds regardless of packets.
Q10	Mail server in DNS	`MX`	MX record defines the domain's mail server.
Q11	Protect shared-dir files	`sticky` bit	Only the owner/root can delete (e.g. /tmp).
Q12	ACL with owner/group/other	`minimum` ACL	Just the standard perm bits as ACL entries.
Q13	Archive container	`tar`	Bundles files/dirs; .tar convention.
Q14	Bash arithmetic	`let`	Performs integer arithmetic.
Q15	Makefile parts	`dependencies`	Targets, dependencies, and commands.
Q16	Analyze connections [legacy]	`Traffic-vis`	Modern: iftop / nload / nethogs.
Q17	Remove svc from init [legacy]	`chkconfig apache2 off`	SysV/SUSE; modern: systemctl disable apache2.
Q18	Stop apache2 [legacy]	`rcapache2 stop`	SUSE rc-script; modern: systemctl stop apache2.
Q19	Swap partition entry	`/etc/fstab`	Where mounts + swap are declared.
Q20	Frees physical memory	`swap`	Pages unused memory to disk.
Q21	Load over 1/5/15 min	`uptime`	Shows uptime + load averages.
Q22	Shell comment char	`#`	Everything after # on a line is ignored.
Q23	Copy dirs over network	`rsync`	Efficient sync; transfers only changes.
Q24	Name resolution config	`/etc/resolv.conf`	Nameservers + search domains.
Q25	Change a file's ACL	`setfacl`	getfacl to view, setfacl to modify.

Note: question order follows the Post Test (Q1 through Q25).

ALA // Post-Test Review

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