Add user to group

Append user to multiple groups without removing existing ones

usermod -aG docker,sudo alice
tool
linux133 commands
tags
linux

More linux commands

  • Show /proc memory maps
    cat /proc/<pid>/smaps | awk '/^Size/{sum+=$2} END{print sum/1024" MB"}'

    Total virtual memory size of a process from smaps

  • Anonymous huge pages status
    grep -E 'HugePages|AnonHugePages|Transparent' /proc/meminfo

    Check if THP / hugepages are used and configured

  • Disable Transparent Huge Pages
    echo never > /sys/kernel/mm/transparent_hugepage/enabled

    Disable THP at runtime (fix for Redis, MongoDB latency spikes)

  • Show NUMA topology
    numactl --hardware

    NUMA nodes, CPU assignment, and memory distribution

  • TCP tuning: increase backlog
    sysctl -w net.core.somaxconn=65535 net.ipv4.tcp_max_syn_backlog=65535

    Increase socket listen backlog for high-connection services

all 133 linux commands