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Consolidating the foundation of Linux, linux tips

Posted on Nov 5 2020 Edited on Feb 20 2023 In Linux Tree , Shell

Linux Tips

Record the commands that I use more frequently in the form of a memo, and will continue to increase according to usage in the future.

#	Commands	Comment
Basis:
	`shopt -s histappend`	Sync history in multiple terminal
	`shopt -s cdspell`	Correct the typos of cd
	`export`, `mount`, `set`	Check the defined value
	`&&`	run the following command only when the previous is successful
	`;`	run the following command regardless of success of first one
	`which <cmd>`,`file <file>`,`command -V <cmd>`	Examine executable file
	`pushd [-n] <dir>`,`dirs -l -v` `popd [-n] [+N \| -N]`	Manage directories with stack
	`dmesg -w`	Wait for new messages
	`less -N +F`	view logfiles and number the lines
	`ls -ld`	list directories themselves, not their contents
	`flock -xn "/tmp/f.lock" c "filename.sh"`	Lock ‘filename.sh’ with flock
	`LANG=C stat file`	Display file status in English
	`time <cmd>`	run and summarize system resource usage of <cmd>
	`tac`	conatenate and print files in reverse,`cat -n file
	`r`	repeat the previous cmd
	`bash -i script`	Make the shell interactive
	`shred -u <file>`	Overwrite file and remove it, better way to delete than ‘rm -rf file’
	`nl`	number lines of contents, `ls \| nl -s ":" -w 1`
	`split <prefix>`, `cat preifx* > file`	split , merge file
	`killall`	kill processes by name
	`fc`	fix and execute commands from history in editor
	`Ctrl-X-E`	execute commands in editor
	`touch -t 2104250101 <file>`	Change the timestamp of file
	`touch -r <file1> <file2>`	file1’s times instead of current time
	`Ctrl-D`	Stop current cmd or bash …
	`dd`	Convert and copy a file, ‘man dd’
	`hexdump, hd -C <binary>`	ASCII, decimal, hexadecimal, octal dump
	`select-editor`	Choose the default editor
	`ranger`	man ranger, ‘?’ in ranger
	`sl -F`	A funny command
	`apropos`	search the manual page names and descriptions,eg:`apropos "list directory"`
	`echo > /dev/<udp or tcp>/<server ip>/<port>`	Check net
	`2>&1`	2 means stderr, &1 means stdout
	`bind -p`	to check the shortcut
	`Ctrl - _`	undo
	`ls -alrRt`	`-r`: reverse, `-R`: Recursive
	`cp -ar(R)pv`	`-p` keep mode,ownership,timestamps; `-r` equals `-R`
	`tail -nf`	Output the last n line appended data as the file grows
	`more/less`	File perusal filter for crt viewing, `less` opposite of more
	`wc`	Print newline, word, and byte couts for each file,`-l` line
	`tar -czf/cjf`	`-j` bzip2, .tar.bz2, max compression; `-z` gzip, tar.gz
	`whatis <cmd>`	display one-line manual page description
Move:	`Ctrl - t`	swap two characters
	`!!`, `!-1`	Refer to the previous command
	`!*` or `Alt+.`	Refer to the previous parameters
	`Ctrl-R`	Search command from history, doulbe to search next
	`ALT - t`	swap two words
	`ALT - .`	prints last argument from previous command
	`Ctrl - x - *`	expand glob/star
	`Ctrl - arrows`	move forward a word
	`ALT - f`	move forward a word
	`ALT - b`	move backward a word
	`Alt-Backspace`	delete forward a word
	`Ctrl - x , Ctrl - e`	Edit command with editor
	`Ctrl - e`	move cursor to end
	`Ctrl - a`	move cursor to start
	`Ctrl - P, N, B, F`	Move previous, next, backward a char, Forward a char
	`Ctrl - xx`	move to the opposite end of the line
	`Ctrl - u`	cuts everything before the cursor
	`Ctrl - k`	cuts everything after the cursor
	`Ctrl - y`	pastes from the buffer
	`Ctrl-W`	cuts one word before the cursor
	`Ctrl - L`	clears screen
	`Ctrl - shift - c/v`	copy/paste into terminal
	`Ctrl-Insert`, `Shift-Insert`	copy/paste
	`Ctrl-Z`,`fg`, `bg`	Pasue the current process, foregroud/backgroud it
System:
	`lscpu`, `cat /proc/cpuinfo`	information about cpu
	`ps [-eLf]`	Get information about process including threads
	`pstree -p, -a`	Get information about process with tree
	`nice`, `renice`	alter priority of process
	`ulimit -a`	get and set user limits
	`free -m`, `cat /proc/meminfo`	information about memory
	`lsblk`, `cat /proc/partitions`	formation harddisk and partition
	`df -h`	infromation about partition
	`mount \| column -t`	status about mounted partition
	`hostname`	show or set the hostname
	`w`	show who is logged on and what they are doing
	`id`	print user and group IDs
	`last`	show a listing of last logged in users
	`cut -d: -f1 /etc/passwd`	show all users
	`cut -d: -f1 /etc/group`	show all groups
	`chkconfig ?list \| grep on`	show all on system service
	`uptime`	show operation time,user number,load
	`ls`, `du`, `ln`, `rmdir`, `rm`, `cp`, `mv`, `cat`, `tail`, `less`, `grep`, `find`
	`htop`, `top`	display processes, 1 - extend top information
	`sudo dpkg --get-selections \| grep linux-image` `cat /proc/version` `grep menuentry /boot/grub/grub.cfg`	Kernel version
	`apt-cache search package`	query the APT cache
	`apt update`
	`uname -a , -r` `cat /proc/version` `cat /etc/issue` `lsb_release -a`	print system information
	`apt upgrade`
	`apt autoremove`
	`apt install update-manager-core`
	`do-release-upgrade`
	flameshot``flameshot gui	Capture screen
	`Ctrl + Alt + F1/../F7`	Enter or quit terminal
	`killall <nautilus>`	Kill file manager
	`pkill Xorg`, `restart lightdm`	Log out
	`$(date "+%Y%m%d-%H%M%S")`	Get the current system time
	`sshfs user@ip:/dir name`	mount sshfs
	`fuser mount -u name`	unmount sshfs , `umount -l name` for busy error
Supper Mode:
	`rename 's/old_name/new-name/' *.txt`	rename files
	`cp \| mv test.sh{,.bk}`, `mv test{.sh,}`	rename quickly, remove suffix
	`find . -type f -exec cat {} +`	`find` and `cat` flies recursively
	`find . -type f -exec ls {} +`	`find . type f -exec ls {} \;`
	`find ./ -type f -exec sed -i 's/old/new/g' {} \;`	Replace all old in the current directory with new
Performance:
	`swapon --show`	Check swap space
	`swapoff -a` `dd if=/dev/zero of=/swapfile bs=1G count=8` `mkswap /swapfile` `swapon /swapfile` `grep SwapTotal /proc/meminfo`	Extend swap space to 8G
	`free -h`
	`top`,`htop`	Interactive process viewer
	`vmstat`	Report virtual memory statistics
	`pmap`	Report memory map of a process
	`kmemleak`	Embeded memeory analysis tool
schedule:
	`at <time>` +	Execute some commands on
	`cron`	Daemon to execute scheduled commands,`/etc/cron.*, /etc/ancrontab`
	`crontab -e`,`crontab -l`	Edit, list the scheduled commands
	`anacron`	run commands periodically
Directory:
	`/var/cache/apt/archives/`	All archived debs
	`hexedit`,`hex`	Hexdump
	`xxd`	Make a hexdump or do the reverse
	`strings -a`	`-a` Scan the whole file
	`cpio -if`	Copy files to and from archives
Network:
	`lspci \| grep -i 'eth'`	Information about eth
	`ifconfig -a`	information about all net port
	`ethtool eth0`	Details of eth0
	`ping <remote host address>`
	`ssh`, `sshfs`, `scp`	remote login, mount, copy
	`iptables -L`	information about firewall
	`service iptables status`	status about firewall
	`service iptables stop`	Close firewall
	`route -n`	show the IP routing table
	`netstat -lntp,-antp,-s,-at,-au,-lt`	information about port,conection,…
Others:
	`addgroup lee vboxusers`	Make virtual box recognize USB
	`*/?/[xyz]/[^xyz]/[!xyz]/[a~z]`	Regular expression
	`make > /dev/null`
	`while true; do adb shell cat /proc/interrupts \| grep kgsl; sleep 0.5; done`
	`adb shell cd sdcard nohup watch -n 5 'cat /sys/bus/cpu/devices/cpu0/online >> online.log' &`
	`readelf -h vmlinux`
	`nm`	List symbols from object files， `nm -n vmlinux
	`ldd`	Print shared object dependencies, list dynamic dependencies, likes xxx.so
	`objdump`	Display information from object files, disassembler
	`ndisasm -u`	The Netwide Disassembler, an 80x86 binary file disassembler
	`c++filt`	Demangle C++ and Java symbols
	`hexdump, hd`	ASCII, decimal, hexadecimal, octal dump， `hexdump -s 0x18408a8 -n 1024 vmlinux`
	`file`	Determine file type, `file .img, .mbn, *.bin ...`
	`readelf`	Displays information about ELF files,`readelf -hlSVAI vmlinux`
	`objdump`	Display information from object(files) `xxx-objdump -afphG vmlinux`
	`objcopy`	Copy and tranlate objects, eg:Generate zImage with vimlinux
	`[android-unpackbootimg](https://github.com/anestisb/android-unpackbootimg) -i boot.img -o boot_img/`
	`python3 [extract-dtb.py](https://github.com/PabloCastellano/extract-dtb)` kernel	Get dts from kernel
	`dtc -I dtb -O dts ... -o ...`	Disassembler
	`od`	Dump files in octal and other formats
	`vim -b file` + `:%!xxd -u` + `:%!xxd -r`	Edit ELF file, `-u` to hex, `-r` to binary
	`ltrace`	A library call tracer
	`strace`	Trace system calls and signals
	`gdb`	The GNU debugger
	`strip`	Discard symbols from object files
	`lsof`	List open files opened by processes
	`fuser`	Identify processes using files or sockets
	`/proc`	Process information pseudo-filesystem
	`ELF`	Format of Executable and Linking Format(ELF) files

Add default CDPATH

export CDPATH='$CDPATH:...'
export CDPATH='~:/var/log:/etc'
lee@lee-pc:~$ cd fonts
/etc/fonts

Modify user

1	sudo chown -R $(whoami) file

Get IP and Netmask

# IP
hostname -I
ifconfig | grep -Eo 'inet (addr:)?([0-9]*\.){3}[0-9]*' | grep -Eo '([0-9]*\.){3}[0-9]*' | grep -v '127.0.0.1'

# Netmask
ifconfig | sed -En 's/255.0.0.0//;s/.*netmask (addr:)?(([0-9]*\.){3}[0-9]*).*/\2/p'

# Only wlan0
ifconfig wlan0 | ...

others

1	ls /proc/device-tree/soc/leds-gpios/