All commands in order

In order of when they are shown in the b09 slides

LS

ls command

pwd and cd

ls

ls -l prints more information ls -a prints dot files (i.e. it includes file starting with .)

cat

• Usually used to dump files
• One file by itself doesn’t really concatenate anything… lol
• But with many files it prints everything from them depending on their contents cat file1 file2 file3

less

lets you view a file (and you can scroll and things too wow!)

mkdir

lets you make a directory w/ the given parent path and the final directory name

mkdir ../newFolder

• This creates a folder in the same directory as the directory your program is in.
  • So mkdir understands that given your path and name, itll go to said path and create this new folder mkdir ./a/b/c/d does NOT work because the directory does not exist. (there is no a, b, or c to create d in)

cp (copy)

cp myfile newname Or cp file1 file2 newDirName To copy a directory (and its contents) you want to do it recursively with -R

mv (move)

Moves files to another directory mv myFile.txt ./myDirectory ./newDirectory

Also used to rename: mv myFile.txt nuclearWeaponCodes.txt

• You cannot rename more than 1 file at a time. Any more than 2 arguments implies you’re just tryna move files to another directory

rm and rmdir

• rmdir removes a directory, but they gotta be empty before you can delete them
• rm just deletes a files
  • You can recursively delete with rm -r and that will delete everything within a directory

Week 2-3

echo

”The print command” Takes a string and prints it out. if passed a variable or other expandable things, it will do expansion first before printing it out

By default, adds a new line to the very end of what you’ve echod. More than 1 spaces between arguments are ignored

• You can keep spaces with \ . Stack em with \ \ \ \ to get lots of spaces.

sh

Runs the script right after as a shell script (creates a shell instance) Different from the . dot command

shift

Shifts the “positional parameters” (the “arguments” as I say)

tr does lots of string manipulation (“replace”)

echo bazinga | tr a b ⇒bbzingb echo icecream sandwich | tr --delete i ⇒ cecream sandwch

[ (test commands)

Test Commands

seq start end

returns a sequence form start to end i.e. seq 0 3 returns 0\n 1\n 2\n 3 line by line!

getopts

p = (*vector) calloc(sizeof(vector));
if (p == NULL)
{
	printf("Problems have occured!");
	return 1;
}
 
p->dim = d;
p->a = (double*) calloc(sizeof(double) * d);
// cuz we did calloc everything should be 0
if (p->a == NULL)
{
	free(p); // I woulda NEVER caught this!
	printf("Problems have occured!");
	return 1;
}
 
return p;

if (head == NULL)
{
	// wait... nothing to free. LOL
}
listnode *at = head;
listnode *temp = NULL;
 
while (at != NULL)
{
	temp = at->next;
	free(at->a);
	free(at);
	at = temp;
}

goes-in-cheat-sheet-DONE

Week 4 ? Maybe 3 idek

diff

Compares two files (i.e. EXACTLY 2 inputs). Says what is different. If different, exits 1. If same, exists 0. -q for briefer output, and -r to find new changes

• d = delete lines 2 and 3 cuz
• 7c5 = v1’s line 7 is v2’s line 5 but changed

grep

• Uses regex
• Returns every line where a pattern exists `{echo baca ; echo bazinga ; echo baca bazinga ; } | grep baca
• Outputs baca and baca bazinga (NOT bazinga!)

{ echo '2xyz@)' ; echo '9abc@p' ; echo 0aaa@k ; echo aaaa@k ; } | grep '[0-9][a-z][a-z][a-z]@[^)]';  
> 9abc@p  
> 0aaa@k

• A very robust example: First char is num. char’s 2 to 4 are numbers. Must be @. And then anything but ) at the end. Anything longer / shorter would not work!

sort

sort -k "2,2n" to_sort.txt

• The -k flag sorts the second column. The n specifies the second column are numbers (sorting between 101 and 78 as strings, 101 would be “smaller” since its first character is less than 7 is )

find

• Finds a file with a bunch of given directories

find mydir ’!’ ’(’ -mmin +3 -mmin -6 ’)’

• Finds files NOT between 3 to 6 minutes ago

Other useful ones

tee: Used to output to more 2+ files

• Takes a file. Reads from stdin. Whatever is inputted from stdin is outputted to the given file and it is thrown into stdout for another command to pipe from
• ls -l | tee out.txt | cat
  • Outputs to out.txt and cat

wc: Gives character, word, and line count

--lines only gives # of lines. Same with -c for characters and -w for words. Also -c counts new lines per line so account for those: echo bazinga | wc -c would be 8

yes prints a word infinitely

comm file1 file2 prints what’s unique to a SORTED file1, file2, and what is common, in 3 nice columns