Deprecated Linux Commands: What to Use Instead

Deprecated Linux commands are why ifconfig throws "command not found" on a fresh server. Nothing is broken. Those classics were retired, and their replacements, mostly the ip command from iproute2, plus ss, grep -E and systemctl, are already on your system.

Modern Replacement Syntax

The first time I SSH'd into a new Ubuntu cloud box and typed ifconfig out of pure muscle memory, I honestly thought the image was broken. It wasn't, net-tools just hadn't shipped by default for years. Below you'll find 17 deprecated Linux commands, each next to its replacement, with real output, so you can retrain your fingers and fix old scripts. If you like this kind of upgrade, the modern Linux tools list is worth a look too.

How to Install Replacements for Deprecated Linux Commands

Good news, you probably have the replacements for most deprecated Linux commands already. iproute2 ships on basically every distro. iw, ethtool, rsync and chrony sit in the standard repos if a minimal image left them out. Heads up on Ubuntu: installing chrony removes systemd-timesyncd, which is expected.

1. Replace ifconfig With ip addr to Check IP Addresses

Of all the deprecated Linux commands, this is the one that trips everyone up. Spin up a minimal Ubuntu 24.04 server on pretty much any host, a Verpex VPS or a local VM, and net-tools just isn't there. ip addr show is the direct swap, and -br gives you a tidy one-line-per-interface view.

You can shorten it to ip a once it sticks. For a wider tour of the tools around it, see these Linux networking commands.

2. Bring an Interface Up or Down With ip link

ifconfig enp2s0 down becomes ip link set enp2s0 down. Same idea, just a different verb order. Try it on a spare interface, not the one your SSH session rides on.

Watch for LOWER_UP. That flag means the cable (or virtual link) actually has carrier, not just that the interface is enabled.

3. Change an IP Address Without Stacking a Second One

Before you touch any address on a remote box, check one kernel setting. When the primary IP on an interface is deleted, Linux also drops every secondary IP in that subnet unless promote_secondaries is on. Lots of systemd based distros already set it to 1, but I'd never bet an SSH session on that. Check it and turn it on first.

Now the mistake I see most from people coming off ifconfig. With ifconfig, setting a new address replaced the old one. So they run ip addr add expecting the same thing.

192.168.1.50 got promoted to primary instead of vanishing. If you're logged in through 192.168.1.10 itself, deleting it still drops you, so reconnect on the new address first or do it from the console. And nothing done with ip survives a reboot, make it permanent with netplan on Ubuntu or nmcli on RHEL and Rocky Linux (see example 14).

4. Replace route With ip route

route -n becomes ip route show, and adding a route is ip route add. The bonus you didn't get before is ip route get, which tells you exactly which path the kernel will pick for a destination.

When someone says "traffic is going the wrong way", ip route get settles the argument in about two seconds.

5. Replace arp With ip neigh

The ARP table lives under ip neigh now. It also shows neighbor state, which arp never did well.

A FAILED entry usually means the host is down or you're on the wrong VLAN. Handy when a server "can't reach" a neighbor.

6. Replace netstat With ss to Find Listening Ports

netstat -tulpn maps almost flag for flag to ss -tulpn. ss reads straight from the kernel, so it's noticeably faster on busy boxes with thousands of sockets. Run it with sudo or the Process column stays empty.

The filter syntax is where ss really pulls ahead. There's a lot more in our full ss command guide, and if you just need to know which process uses a port, that one has you covered.

7. Replace netstat -i With ip -s link

Interface counters used to come from netstat -i. Now it's ip -s link. The other netstat modes moved too: -r is ip route, -g is ip maddr, and -s is nstat.

Climbing errors or dropped numbers on RX are worth chasing. Bad cable, duplex mismatch, or a ring buffer that's too small.

8. Replace iwconfig With iw for Wireless Info

iwconfig belongs to wireless-tools, which hasn't really moved in a long time and doesn't understand newer Wi-Fi standards properly. iw talks nl80211 and shows the real link details.

Anything around -50 to -60 dBm is a solid signal. Past -75 and you'll start feeling it.

9. Replace mii-tool With ethtool for Link Speed

mii-tool came from net-tools too, and it only knows older PHYs well. ethtool reports speed, duplex and link state on anything modern.

If a gigabit server shows Speed: 100Mb/s, check the cable or switch port before you blame the application.

10. Replace egrep and fgrep With grep -E and grep -F

Since GNU grep 3.8, egrep and fgrep print an "obsolescent" warning every single time. Harmless at the prompt, annoying in cron mail. The fix is just the flag. I'm piping from journalctl here because Debian 12 and plenty of minimal images don't ship /var/log/syslog anymore, the journal is where the logs live.

-F matters with patterns like [ERROR], since the brackets are otherwise read as a regex character class. More pattern tricks in how Bash uses grep for text processing.

11. Replace service and chkconfig With systemctl

On any systemd distro, service and chkconfig are just wrappers now. On Rocky Linux you can actually watch chkconfig hand the job over.

enable --now is the one to remember. If a unit refuses to start after that, this guide on how to fix systemd service errors walks through the usual suspects.

12. Replace apt-key With a signed-by Keyring

apt-key trusted a key for every repo on the system, which was a real security hole. It now prints a deprecation warning on Ubuntu 24.04, and its own man page says Debian 12 and Ubuntu 24.04 are the last releases that ship it. Store the key per repo and point to it with signed-by.

The $(...) bits fill in your architecture and release codename, so the same line works on 22.04, 24.04 or whatever you're on. On Debian, swap /linux/ubuntu for /linux/debian in both URLs.

13. Replace yum With dnf on RHEL and Rocky Linux

yum still "works" on RHEL 8, 9 and 10, but it's just a symlink to dnf. Ask both for a version and you get the same answer. Old muscle memory is fine at the prompt. For docs and new scripts, write dnf. On Fedora 41 and newer, dnf itself is now dnf5, so the output looks a little different there.

Coming from the Debian side? The dnf vs apt comparison maps the common commands between the two.

14. Replace ifup, ifdown and network-scripts With nmcli

RHEL 9 and Rocky Linux 9 dropped the legacy network-scripts package, and ifcfg files are deprecated in favor of NetworkManager keyfiles. If ifup still exists on your box, it's a thin wrapper around nmcli. This is also the persistent fix for the IP change in example 3.

15. Replace Legacy scp Transfers With rsync or sftp

The scp command itself isn't gone. Since OpenSSH 9.0 it quietly uses the SFTP protocol, because the old scp protocol was outdated and hard to fix. For big or repeat transfers, rsync is the better habit anyway, it resumes and only sends what changed.

If an ancient remote server rejects the new behavior, scp -O forces the legacy protocol. Pair rsync with passwordless SSH login and it drops straight into cron.

16. Replace ntpdate With chronyc

ntpdate was removed from RHEL 8 onward. chrony handles the one-shot sync it used to do, plus the ongoing sync.

Leap status : Normal means you're synced. "Not synchronised" means chrony can't reach any source, usually a firewall blocking UDP 123.

17. Find Deprecated Linux Commands Hiding in Your Scripts

This is the real-world payoff. Old scripts are where deprecated Linux commands actually hurt you, usually on the day you migrate to a fresh server. Sweep your script directory first.

Then rewrite each hit. Here's line 14 done with ip, which gives you a clean address with no net-tools dependency:

Conclusion

Most of these swaps come down to ip, ss, grep flags and systemctl, and after a week or so they stop feeling new. Clean up your scripts now, before a fresh server does it for you. For the bigger picture on networking day to day, the Linux network administration guide is a good next read. Which of these deprecated Linux commands was hardest for you to give up? Share your experience in the comments below.

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