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Package

  • dpkg -c: list contents of deb package, dpkg -x: extract files from package, dpkg -L: list files installed from a package-name
  • dpkg -s filename: search for a filename from installed packages
  • apt-file search filename: search which package contains a specific file/path
  • apt-get -o Dpkg::Options::="--force-confmiss" install --reinstall <package-name>

File

  • zip -r dir.zip dir [-x dir/node_modules\* dir/.git\*]
  • unzip dir.zip
  • tar czvf dir.tar.gz dir [--exclude node_modules --exclude .git]
  • tar xzvf dit.tar.gz -C dir
  • tar: omit -v to see error info, filename should follow -f directly
  • locate: find files by name, updatedb
  • whereis: locate the binary, source, and manual page files for a command
  • find ./ \( -path ./node_modules -o -path ./.git -o -path ./.idea \) -a -prune -o -print | xargs wc -l | sort -n: -a means and, -o means or
  • find . -mtime +30 | xargs rm -rf: delete files older than 30 days
  • ls -tr
  • convmv -r -f cp936 -t utf8 --notest --nosmart *
  • iconv -f UTF-16LE -t UTF-8 utf-16leEncodiedFile > output
  • rsync -lptzr --delete src_dir/ dst_dir: -l sysmlinks, -p perms, -t times, -z compress

Text

  • sort -k3 -r -n -h: -k3 => third column, -r reverse, -n numeric sort, -h human numeric sort
  • tr: translate or delete characters
  • sed -i 's/ugly/beautiful/g' filename: edit file in place to replace ugly with beautiful
  • strings: pint the strings of printable characters in files
  • expand: convert tabs to spaces
  • tee: read from standard input and write to standard output and files
  • grep -r "word" /path/to/dir/*.c, find . -type f -exec grep -l "word" {} +, find /path/to/dir -type f -print0 | xargs grep -l "foo": recursively search all files for a string, find -print0 can deal with spaces in file names
  • egrep -v 'exclude1|exclude2'
  • find -L /etc/ssl/certs -type l -delete

Disk

  • fdisk -l: List the partition tables for the specified devices. If no devices are given, those mentioned in /proc/partitions (if that exsts) are used
  • df -h: report file system disk space usage
  • du -sh target_dir: estimate file space usage
  • du --max-depth 1 -h | sort -rn | head -n 5: top 5 big dir/file
  • mount -t cifs -o username=USERNAME,password=PASSWORD //HOST/SHARE_NAME /mnt/MOUNT_POINT: mount smb share folder
  • hdparm -t /dev/sda6: perform timings of device reads for benchmark and comparison
  • blockdev --report: print a report for the specified device
  • blockdev --getra /dev/sda, blockdev --setra /dev/sda: get/set readahead, in sectors
  • blockdev --getbsz /dev/sda, blockdev --setbsz /dev/sda: get/set block size, in bytes
  • lsblk -o NAME,PHY-SeC, cat /sys/block/sda/queue/physical_block_size: get block device physical sector size

Network

Config

  • resolvconf -u
  • route: show / manipulate the IP routing table
  • route add -net 10.0.0.0 netmask 255.0.0.0 gw 192.168.225.173: add static route
  • arp: manipulate the system ARP cache
  • arp -D test6; arp -d test6; arp -s test6 MAC_addr
  • dig +short HOSTNAME

Diagnose

  • ip: show/manipulate routing, devices, policy routing and tunnels
  • curl ifconfig.me: figure out external ip
  • ip -4 route get 8.8.8.8: figure out which interface is used to comunicate with certain host
  • traceroute -I HOST
  • nslookup: query Internet name servers interactively
  • dig: DNS lookup utility
  • mtr: a network diagnostic tool
  • netstat -s | grep -E '.*(queue|timeout).*'
  • tcpdump -A -s 0 -n -i lo host localhost and port 7070
  • ssh user@remotehost tcpdump -s 0 -n -U -w - -i any host ? | wireshark -k -i -
  • ss -m src *
  • cat /proc/net/sockstat：TCP mem about equal ss -m src *
  • nmap -sP 192.168.1.*

iptables

  • iptables -t nat -A OUTPUT -d 1.1.1.1 -j DNAT --to-destination 2.2.2.2
  • iptables -t nat -D OUTPUT -d 1.1.1.1 -j DNAT --to-destination 2.2.2.2

Service

  • service SCRIPT COMMAND: run a System V init script(/etc/init.d/) or an upstart job(/etc/init) (take precedence).
  • All scripts should supportat least the start and stop command.
  • upstart jobs: restart => stop => start, init scripts
  • upstart jobs: initctl list, init scripts
  • update-rc.d SCRIPT enable/disable, chkconfig: enable or disable system services

SSH

  • ssh -NfD [local_addr]:7070: forward localhost's 7070 port to remotehost, dynamically
  • ssh -NfL [local_addr]:7070:remote_addr:22 user@remotehost: forward localhost's 7070 port to remotehost's 22 port, default local_addr is loopback
  • ssh -NfR [remote_addr:]7070:local_addr:22 user@remotehost: forward remotehost's 7070 port to localhost's 22 port, default remote_addr is loopback, if want it to be the others, turn GatewayPorts on in /etc/ssh/ssd_config, then reload ssh
  • ssh-keygen -R hostname: remove all keys belong to hostname from a known_hosts file
  • ssh-copy-id [-i [identity_file]] username@remotehost: install your public key in a remote machine's authorized_keys

GIT

  • git commit --amend --author "name <email>": modify last commit

  • git rebase -i master~3: interactive rebase

  • git log：-p --color | --graph | --pretty=oneline

  • git diff HEAD: diff staged and unstaged changed files

  • git submodule, git add path/to/submodule, `git rm --cached path/to/submodule

  • git clone -b branch_name

  • git checkout -b branch_nae remote/branch_name, git checkout --trach remote/branch_name

  • git remote prune origin, git remote update

  • rewrite commit histroy

    git filter-branch --commit-filter '
if [ "$GIT_COMMITTER_NAME" = "wrong_name" ];
then
    GIT_COMMITTER_NAME="inetfuture(Aaron Wang)";
    GIT_AUTHOR_NAME="inetfuture(Aaron Wang)";
    GIT_COMMITTER_EMAIL="inetfuture@gmail.com";
    GIT_AUTHOR_EMAIL="inetfuture@gmail.com";
    git commit-tree "$@";
else
    git commit-tree "$@";
fi' HEAD

VIM

  • set tabstop=4, set nospell
  • 2yy, p
  • G or g: go to the end/start of the file
  • Ctrl + g: show file information
  • / or ?: forward or backward search, n or N: next or previous
  • 10j: 10 lines forward,10k: 10 lines backward
  • o or O: insert a new line below or above this line

Mail

  • msmtp -S --host serverhost: check information about SMTP server
  • nslookup -query=mx redhat.com
  • telnet POP3-server 110: commands: user, pass, stat, list, retr, dele(take effect after quit), quit

openssl

  • openssl x509 -text -noout -in PEM_FILE_PATH

PHP

  • php --ini: show configuration file names
  • php --interactive
  • php -m | grep ext_name: check extension
  • php-config : get information about PHP configuration and compile options
  • pear config-set http_proxy http

Hardware

  • rfkill: tool for enabling and disabling wireless devices
  • lshw -C network
  • lspci / lsusb: list all PCI / usb devices
  • alsamixer: soundcard mixer for ALSA soundcard driver, with ncurses interface

Performance Monitoring

  • iostat -xm 2
  • iotop
  • ps aux --sort -rss

Miscellaneous

  • lsmod: show the status of modules in the linux kernel
  • ln -sf /usr/share/zoneinfo/Asia/Shanghai /etc/localtime: set time zone, date -R
  • useradd testuser -m -s /bin/bash
  • usermod username -Ga sudo, groups username
  • lastlog: reports the most recent login of all users or of a given user
  • history | awk '{a[$2]++}END{for(i in a){print a[i] " " i}}' | sort -rn | head
  • gnome-terminal --geometry 110x30+1000+1000 --hide-menubar
  • update-alternatives --config editor
  • x11vnc --create --forever