Misc. Linux commands.
Current directory
Find x-days before and action
In actuality, it should be (x-1).
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/bin/find <path> -maxdepth 1 -mtime +<x> -type f -name "<pattern>" -exec rm -f {} \;
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Find x-minutes before and action
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/bin/find <path> -maxdepth 1 -mmin +<x> -type f -name "<pattern>" -exec rm -f {} \;
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Change password last modify
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chage -d YYYY-MM-DD <user>
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Change password never expire
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chage -I -1 -m 0 -M 99999 -E -1 <user>
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Lock/Unlock Account
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passwd -l <user> # Lock
passwd -u <user> # Unlock
usermod -L <user> # Lock
usermod -U <user> # Unlock
pam_tally2 -r -u <user> # Reset fail login count
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iptable ban ip
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iptable -A INPUT -s <IP> -j DROP
ip6table -A INPUT -s <IP> -j DROP
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Fail2ban ban ip manually
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fail2ban-client status # show jail list
fail2ban-client -vvv set <jail from list> banip <ip>
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zsh range for loop
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for i in {1..10};do .....
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bash string comparison
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if [ "$str" = "string" ]; then ...
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bash/zsh numeric comparison
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if [[ ${A} = 3 ]]; then echo yes; fi
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Disable journal on ext4
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tune2fs -O ^has_journal /dev/<disk>
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Rotate frame buffer
Number can be 1, 2, 3
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echo 1 > /sys/class/graphics/fbcon/rotate_all
echo 1 > /sys/class/graphics/fbcon/rotate
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Show all mDNS/Bonjour entries
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avahi-browse -a
avahi-browse -a -d <domain> # specify domain other than .local
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Create sparse file
truncate -s <size> <filename>
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$ truncate -s 10G 10G.txt
$ ls -lah 10G.txt
-rw-r--r-- 1 user user 10.0G Apr 1 00:00 10G.txt
$ du -sh 10G.txt
0 10G.txt
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Ref: Sparse file wikipedia
Rsync
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rsync -vahpt --size-only --stats --del <source> <target>
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<source> is put/sync INTO <target> directory, not replacing <target>.
Curl skip certificate checking
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curl -k ... # Use -k to skip certificate check.
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Resize Filesystem
Usually use after a partition / image resize
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resize2fs <device>
resize2fs /dev/sda1
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avahi/mdns lookup
Get IPv4 mdns
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avahi-resolve -n4 door.local
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Get IPv6 mdns
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avahi-resolve -n6 door.local
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Check NIC status
Enable BBR
Create file /etc/sysctl.d/10-network-bbr.conf with following content and reboot:
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net.core.default_qdisc=fq
net.ipv4.tcp_congestion_control=bbr
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SSH remove from known hosts
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ssh-keygen -R <hostname/ip>
ssh-keygen -f "~/.ssh/known_hosts" -R <hostname/ip>
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Echo Multiple Lines (Bash)
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STR="Line 1
Line2"
# This will output all in one line
echo $STR
Line 1 Line 2
# Use ""
echo "$STR"
Line 1
Line 2
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