Linux Commands - Revision history

Beard at 04:57, 3 August 2020

2020-08-03T04:57:23Z

Beard at 15:51, 2 January 2020

2020-01-02T15:51:58Z

Beard at 21:54, 8 November 2019

2019-11-08T21:54:40Z

Beard at 21:00, 17 September 2019

2019-09-17T21:00:10Z

Beard at 20:46, 6 August 2019

2019-08-06T20:46:13Z

Beard at 17:17, 29 July 2019

2019-07-29T17:17:17Z

Beard at 18:26, 24 June 2019

2019-06-24T18:26:34Z

Beard at 19:41, 9 April 2019

2019-04-09T19:41:41Z

Beard at 20:33, 22 January 2019

2019-01-22T20:33:59Z

Beard at 16:53, 4 October 2018

2018-10-04T16:53:36Z

@@ Line 1: / Line 1: @@
-Updated 1/2/2020
+Updated 8/2/2020
 <pre>
@@ Line 173: / Line 173: @@
 	-c-N - where N is the number of characters to cut off at the end
 tail - print the tail of the input
-	-N - where N is the number of lines
+	-N - where N is the number of lines (ie. "tail -2")
 	-cN - where N is the number of characters
 	-c+N - where N is the number of characters to cut off at the beginning
@@ Line 747: / Line 748: @@
 history - list of previous commands
 fc -l - list of previous commands
 fc -s <#> - re-execute command
@@ Line 783: / Line 785: @@
 restorecon /dir - restores selinux labels. use on dirs like /var if you move them.
 fixfiles relabel /dir - same as restorecon. worked before.
 chmod <perms> <file> - set a file's permissions
@@ Line 900: / Line 925: @@
 	<runlevels> - specify runlevels to enable/disable for (ie "23" will specify runlevels 2 and 3)
-;read - pause and wait for input
+read - pause and wait for input
-to make a function:
+to make a function (2 different ways):
-	function(){
+	function_name(){
-	commands
+		commands
 	commands
+	}
@@ Line 920: / Line 947: @@
 to catch errors:
-	if ! 'command';then
+	if 'command';then
 		echo ERROR
 	fi 2>/dev/null
@@ Line 1,210: / Line 1,237: @@
 		complete -F _vb_complete vb
 set - set command
 	-x - set debug mode inside the script (xtrace on)

@@ Line 1: / Line 1: @@
-Updated 11/8/2019
+Updated 1/2/2020
 <pre>
@@ Line 329: / Line 329: @@
 showmount <host> - shows hosts with shares or shows shares on <host>
 	-a - show all
 losetup <target> <source> - setup a loop device, can map a partition from a disk image
 	-o <offset> - offset of partition from file (fdisk: sector size * start)
@@ Line 593: / Line 595: @@
 nuitka --portable script.py - python compiler. Compiles a Linux executable from script.py
 apt-get update - update package lists

@@ Line 1: / Line 1: @@
-Updated 9/17/2019
+Updated 11/8/2019
 <pre>
@@ Line 1,164: / Line 1,164: @@
 	complete -S suffix command - added to end of each completion listed
 		-o <option>
-			bachdefault - perform the default Bash completion if no matches
+			bashdefault - perform the default Bash completion if no matches
 			default - use default filename completion if no matches
 			dirnames - directory name completion if no matches
@@ Line 1,172: / Line 1,172: @@
 			nospace - do not append spaces to end of lines
 	/etc/bash_completion.d - you can place completion scripts in here, and they will be sourced when an new bash shell is executed.
 set - set command

@@ Line 1: / Line 1: @@
-Updated 8/6/2019
+Updated 9/17/2019
 <pre>
@@ Line 141: / Line 141: @@
 <command> < <filename> - sends contents of file to command
 <command1> | <command2> - feed output of com1 into com2
 |tee <file> - puts output into file and echos
 > <place> - redirect standard output
@@ Line 717: / Line 718: @@
 for x in 'jobs -p';do kill -9 $x;done - kill all jobs
 WHITESPACE PROBLEM - $IFS is used to determine field separator. It usually includes all whitespace, so to process line by line, do this:
 	s=$IFS
@@ Line 1,139: / Line 1,152: @@
 reset - reset shell defaults
 set - set command
 	-x - set debug mode inside the script (xtrace on)

@@ Line 1: / Line 1: @@
-Updated 7/29/2019
+Updated 8/6/2019
 <pre>
@@ Line 273: / Line 273: @@
 free -m - memory info in MB
 lshw - list hardware
-lspci -v - list extensive hardware info
+lspci [-d <vendor>:<device>:<class>] - PCI bus/device info (/proc/bus/pci/*/* and /sys/bus/pci/devices/pci0000::00/*)
 lsusb - list USB devices
 ipcs -a - list IPC ramdisk usage. Ramdisk is mounted at /run. (IPC: Inter-Process Communication)
@@ Line 936: / Line 951: @@
 		EXIT      -- Exit signal of any kind
-if <!> [ <?> yada yada ]
+if <!> [ <!> <?> yada yada ] - tests
 	-e - if exist
 	-f - if file
@@ Line 954: / Line 969: @@
 	-z - if zero length
 	-n - if non-zero length
-	f1 -nt f2 - if newer than
+	! - negation (also tests if command produces error)
-	f1 -ot f2 - if older than
-	f1 -ef f2 - if both links to same file
+if <!> [ <!> expr1 <?> expr2 ] - combining expressions
 	! - negation (also tests if command produces error)
@@ Line 1,056: / Line 1,076: @@
 let a||b  - logical OR: returns true if a OR b
 let a?b:c - conditional: if a then b else c
 # Bitwise operations
 printf "0x%x\n" $(( 0x01 << 1 )) - left bit shift
-expr - resolve math and string expressions. only works with integers.
+expr - resolve math and string expressions. doesn't work with float numbers.
 	expr ARG1 < ARG2 - outputs 0 if false, and 1 if true
 	expr ARG1 \< ARG2 - sometimes you need to escape the operator to avoid conflict with shell operators, including parentheses

@@ Line 1: / Line 1: @@
-Updated 6/24/2019
+Updated 7/29/2019
 <pre>
@@ Line 877: / Line 877: @@
 to carry a function over to a subshell (ie. just doing bash -c "function" doesn't work):
 	bash -c "$(declare -f function); function"
-−
 to catch errors:
 	if ! 'command';then
@@ Line 890: / Line 896: @@
 		<commands>
+	}
 	# trap keyboard interrupt (control-c)
 	trap exit_f SIGINT
-	signals:
+if <!> [ <?> yada yada ]
 	-e - if exist
 	-f - if file
@@ Line 919: / Line 953: @@
 	-N - if modified since last read
 	-z - if zero length
-	-n - if null
+	-n - if non-zero length
 	f1 -nt f2 - if newer than
 	f1 -ot f2 - if older than
 	f1 -ef f2 - if both links to same file
-	! - if command produces error (opposite of any test above)
+	! - negation (also tests if command produces error)
 if [ $test1 ];then

@@ Line 1: / Line 1: @@
-Updated 4/9/2019
+Updated 6/24/2019
 <pre>
@@ Line 248: / Line 248: @@
 false - produce 1
-dmesg - kernel dump
+dmesg - bootup message dump
 last - login log
 who - who is currently logged on

@@ Line 1: / Line 1: @@
-Updated 1/22/2019
+Updated 4/9/2019
 <pre>
@@ Line 134: / Line 134: @@
 	- - take from standard input (ie. echo "hello" | cat -)
 tac - print lines in reverse order (similar to cat)
 strings <file> - print any ascii characters in a binary file
@@ Line 146: / Line 147: @@
 &> <place> - redirect both stdout and stderr
 command < infile > outfile - combinations of redirects
 exec 3<>/file - set file as place to redirect 3
 	echo hi >&3 - redirect
@@ Line 307: / Line 310: @@
 			format:	username=<name>
 					password=<pass>
-umount /mnt/mountpoint- unmount the share
+umount /mnt/mountpoint - unmount the share
 showmount <host> - shows hosts with shares or shows shares on <host>
 	-a - show all
@@ Line 548: / Line 551: @@
 	u - undo
 	U - undo line
-	ctl-r - redo
+	ctrl+r - redo
 	x - delete
 	dd - delete line (and save to clipboard; similar to cut)
@@ Line 560: / Line 563: @@
 	:w - save
 	:wq! - save and quit (force)
 	:set number - line numbers (set nu)
 	:set nonumber - no line numbers (set nonu)
@@ Line 869: / Line 873: @@
+	}
 to catch errors:
 	if ! 'command';then
@@ Line 939: / Line 948: @@
 ()    - sub-shell
 $()   - command substitutions
 (())  - arithmetic, "let", used when it contains an 'equals' sign
@@ Line 947: / Line 957: @@
 !(not-this) - anything but this, invert
 	example: ls -d !(Downloads) - list everything EXCEPT Downloads
 parallel processing; wait for sub-shells:
@@ Line 975: / Line 1,006: @@
 	[!a-e] - single character NOT matching a, b, c, d, or e
-a+=b	 - concatenate
+let a+=b  - add
-let a+=b - add
+let a-=b  - subtract
-let a-=b - subtract
+let a*=b  - multiply
-let a*=b - multiply
+let a/=b  - divide
-let a/=b - divide
+let a**b  - exponent (a to the b)
-let a++  - increment
+let a%b   - modulo
-let a--  - decrement
+let a++   - increment
 expr - resolve math and string expressions. only works with integers.
@@ Line 992: / Line 1,035: @@
 	expr index STRING CHARS - find CHARS in STRING
 	( EXPRESSION ) - parenthetical expression
-bc - Precise calculator
+bc - Precise calculator. Works with floats.
 	-l - use full precision
 	echo "2/5*(3.14*8)-2" | bc -l | sed 's/0*$//g' - trim trailing zeros
@@ Line 1,079: / Line 1,122: @@
 	<(-)param> - enable/disable a param (ie. ofdel enables, -ofdel disables)
 infocmp <term> - get info about terminal (terminfo, termcap)
-showkey -a - enter keys to get thir dec/oct/hex value as seen by the terminal (must be root).
+showkey -a - enter keys to get their dec/oct/hex value as seen by the terminal (must be root).
 terminator - multiple terminals in one window, customizable
 tmux - multiplexed terminals in one terminal
@@ Line 1,105: / Line 1,148: @@
 which -a - all instances of executable in PATH locations
-RANGE={1..10} {A..Z} {a..z}
+{1..10} {A..Z} {a..z} - ranges
-LEADING_ZEROS={000..999}
+{10..100..5}% - range 10-100 in units of 5 with "%" after each one (ie. 10% 15% 20% ...)
-${var:-value} - make var default to value if not set (temporary; doesn't save the value)
+{000..999} - range with leading zeros
 ${var:=value} - set var default to value if not set (saves the value)
 ${var:+message} - if var is set, print message. if var is not set, print nothing
@@ Line 1,124: / Line 1,171: @@
 	remove file extension ${FILE%.*} file.txt -> file
 	get directory name from path ${FILEPATH##*.} /dir/file.txt -> /dir
-${var/pattern1/pattern2} - substitute pattern1 with pattern2
+${var/pattern/string} - substitute pattern with string
 ${var,} - make first character lowercase
 ${var,,} - make var all lowercase
@@ Line 1,199: / Line 1,250: @@
 	${array[@]^} - make first char in each item uppercase (ie "hi bob" -> "Hi Bob")
 	unset array[0] - remove array item 0 (no "$" or braces)
 	list="11 22 33"

@@ Line 1: / Line 1: @@
-Updated 10/4/2018
+Updated 1/22/2019
 <pre>
@@ Line 22: / Line 22: @@
 shift + page up or down - scroll
 -- - signifies end of command and beginning of arguments (or last argument)
-ctrl + c - kill process in foreground
+ctrl + c - kill process (SIGINT)
-ctrl + u - kill a line
+ctrl + \ - kill and core dump (SIGQUIT)
-ctrl + l - clear
+ctrl + z - suspend process (SIGTSTP)
 ctrl + alt + f1 - bypass gui
 ctrl + alt + f7 - return to gui
-ctrl + d - logout
+ctrl + d - logout (in GUI) or EOF in terminal
-esc + . - insert parameters from last command
+esc + . - insert all parameters from last command
 ctrl + alt + e - expand all string expansions and show it before executing it
 ctrl + r - search command history
 hold shift during boot to get grub menu
 put commands in .bashrc in home dir to run command at login
@@ Line 335: / Line 339: @@
 steghide - steganography tool. hides/embeds data into other data.
 ffmpeg -i <input.file> <output.file> - extract audio from video. Extension of output file determines output format.
 growisofs -dvd-compat -Z /dev/dvd=/path/to/image.iso - burn image to DVD
 convert file1.png file2.txt outfile.pdf - convert several different file formats to pdf pages

@@ Line 1: / Line 1: @@
-Updated 6/28/2018
+Updated 10/4/2018
 <pre>
@@ Line 45: / Line 45: @@
 	-regex <pattern> - look for pattern (matches whole file path, not just name)
 	-iregex - case insensitive regex
 find /u1/database/prod/arch -type f -mtime +3 -exec rm {} \; - find files that are older than 3 days and remove them
 locate - search
@@ Line 153: / Line 154: @@
 	-cd - count duplicate lines
 	-cu - count unique lines
 diff <file1> <file2> - difference between files
 	-y - side-by-side output
@@ Line 346: / Line 348: @@
 	notrunc - do not truncate
 	noerror - no halt on error
 	kill -USR1 $(pgrep ^dd) - send USR1 signal to dd to get output of its progress (run this from another terminal or with dd running in the background)
 ddrescue <source> <destination> [<logfile>] - dd for damaged drives (from package "gddrescue")
@@ Line 456: / Line 459: @@
 	-u - udp
 	-a - all
-lsof -i - list processes that are listening on the network
+lsof - list open files
 nslookup <hostname/addr> - dns lookup
 dig <hostname> - dns lookup
@@ Line 997: / Line 1,007: @@
 esac
-echo "It's much nicer to use a 'case' than an 'if' for user input."
+echo "This is the best way to accept user input."
-echo "Do you agree? ";read ans
+echo -n "Do you agree? [y,N] ";read ans
 case $ans in
 	[yY]|[yY][Ee][Ss])
-		echo "Then you are wise.";;
+		echo "Then you are insightful.";;
 	*)
 		echo "I see...";;
 esac
-# you may want to use "shopt -s nocaseglob" to make case insensitive ("shopt -u nocaseglob" to unset)
+# you can use "shopt -s nocaseglob" to make case insensitive ("shopt -u nocaseglob" to unset)
 # you can also do ${ans,,} for all lowercase, or ${ans^^} for all uppercase
@@ Line 1,124: / Line 1,142: @@
 x**y - y is exponent of x
 % - remainder ie. $((15%7))
-$((2#<binary>)) - define binary number
+$((<base>#<value>)) - define a number's base
 $((0x<hex>)) - define hex number
 export <var>=<value> - set environment variable