shell

clean files 3 days ago

find /root/database/backup/db.sql.*.gz -mtime +3 -exec rm {} \;

ssh without affect $HOME/.ssh/known_hosts

ssh -o "UserKnownHostsFile /dev/null" root@aliyun.geekcity.tech
ssh -o "UserKnownHostsFile /dev/null" -o "StrictHostKeyChecking=no" root@aliyun.geekcity.tech

rsync file to remote

rsync -av --delete \
    -e 'ssh -o "UserKnownHostsFile /dev/null" -p 22' \
    --exclude build/ \
    $HOME/git_projects/blog root@aliyun.geekcity.tech:/root/develop/blog

looking for network connections

all connections
- ```
lsof -i -P -n
```
specific port
- ```
lsof -i:8083
```

port forwarding with ssh tunnel

local port forwarding

ssh -L [local_port]:[remote_host]:[remote_port] [user]@[gateway] -N -f

sync clock

yum install -y chrony \
    && systemctl enable chronyd \
    && (systemctl is-active chronyd || systemctl start chronyd) \
    && chronyc sources \
    && chronyc tracking \
    && timedatectl set-timezone 'Asia/Shanghai'

settings for screen

cat > $HOME/.screenrc <<EOF
startup_message off
caption always "%{.bW}%-w%{.rW}%n %t%{-}%+w %=%H %Y/%m/%d "
escape ^Jj #Instead of control-a

shell -$SHELL
EOF

count code lines

find . -name "*.java" | xargs cat | grep -v ^$ | wc -l
git ls-files | while read f; do git blame --line-porcelain $f | grep '^author '; done | sort -f | uniq -ic | sort -n
git log --author="ben.wangz" --pretty=tformat: --numstat | awk '{ add += $1; subs += $2; loc += $1 - $2 } END { printf "added lines: %s removed lines: %s total lines: %s\n", add, subs, loc }' -

check sha256

echo "1984c349d5d6b74279402325b6985587d1d32c01695f2946819ce25b638baa0e *ubuntu-20.04.3-preinstalled-server-armhf+raspi.img.xz" | shasum -a 256 --check

check command existence

if type firewall-cmd > /dev/null 2>&1; then 
    firewall-cmd --permanent --add-port=8080/tcp; 
fi

set hostname

hostnamectl set-hostname develop

add remote key

ssh -o "UserKnownHostsFile /dev/null" \
    root@aliyun.geekcity.tech \
    "mkdir -p /root/.ssh && chmod 700 /root/.ssh && echo '$SOME_PUBLIC_KEY' \
    >> /root/.ssh/authorized_keys && chmod 600 /root/.ssh/authorized_keys"

check service logs with journalctl

journalctl -u docker

script path

SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"

query for ip address

# dnf -y install curl jq
curl -sL 'https://www.ip.cn/api/index?ip&type=0' | jq -r '.ip'

extend fedora root partition

example

[root@cloud-template ~]# fdisk -l
Disk /dev/sda: 64 GiB, 68719476736 bytes, 134217728 sectors
Disk model: QEMU HARDDISK
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: D90CD1A6-E818-447F-909B-8EE0135EB122

Device       Start       End   Sectors Size Type
/dev/sda1     2048      4095      2048   1M BIOS boot
/dev/sda2     4096   2101247   2097152   1G Linux filesystem
/dev/sda3  2101248 134215679 132114432  63G Linux LVM


Disk /dev/mapper/fedora-root: 15 GiB, 16106127360 bytes, 31457280 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/zram0: 3.81 GiB, 4090494976 bytes, 998656 sectors
Units: sectors of 1 * 4096 = 4096 bytes
Sector size (logical/physical): 4096 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes

[root@cloud-template ~]# lsblk -f
NAME            FSTYPE      FSVER    LABEL UUID                                   FSAVAIL FSUSE% MOUNTPOINTS
sda
├─sda1
├─sda2          xfs                        65396769-d1e4-4807-862a-9db0a68ef0cf    735.4M    23% /boot
└─sda3          LVM2_member LVM2 001       ddhEGK-SuWg-Xl6y-MhIJ-Ip7e-2FGy-4PqeVg
  └─fedora-root xfs                        cccf36b1-980d-4132-849a-9e02439bc11b     13.2G    11% /
zram0

[root@cloud-template ~]# pvs
  PV         VG     Fmt  Attr PSize   PFree
  /dev/sda3  fedora lvm2 a--  <63.00g <48.00g
[root@cloud-template ~]# lvs
  LV   VG     Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  root fedora -wi-ao---- 15.00g

extend lv and xfs

lvextend /dev/mapper/fedora-root -l+100%FREE
xfs_growfs /dev/mapper/fedora-root

generate random string

tr -dc A-Za-z0-9 </dev/urandom | head -c 16

parquet-tools

references: https://github.com/NathanHowell/parquet-tools
installation
- ```
python3 -m pip install parquet-tools
```

operations

parquet-tools:master show /tmp/file.parquet