PA Note

PA Note

Linux

#
$sudo apt update


# 
$whereis <name>

Vim

0 line start, $ line end

/word search "word", n find next, N find previous

d0 delete until line start, d$ delete until line end, dd cut current line

y0 copy until line start, y$ copy until line end, yy copy current line

p paste register

u undo, ctrl+r redo

gcc

## ref

# https://www.cprogramming.com/gcc.html
# https://www3.ntu.edu.sg/home/ehchua/programming/cpp/gcc_make.html


## Syntax

#
-o outputfile
# enable all warnings
-Wall
# treat warnings as errors
-Werror
# to use by gdb
-g


## Process

# 1.pre-processing
# include headers and expands the macros
$cpp hello.c > hello.i
# 2.compilation
# compile into assembly code for a specific processor
$gcc -S hello.i
# 3.assembly
# convert into machine code
$as -o hello.o hello.s
# 4.linker
$ld -o hello hello.o ...libraries...


## Utilities

# display the type of object files and executable files 
$file <filename>
# lists symbol table of object files
$nm <filename>
# examines an executable and displays a list of the shared libraries that it needs
$ldd <filename>

make

a makefile for hello.c

all: hello

hello: hello.o
	gcc -o hello hello.o

hello.o: hello.c
	gcc -c hello.c

clean:	
	rm hello.o hello

rules

target: pre-req-1 pre-req-2
    command

Run the command if the target is out-dated compared with its pre-requisite.

Note that command must be preceded by a tab.

Note that start the target "all" when running make without argument.

Another version:

# define a macro
filename = hello
all:    $(filename)
    echo ALL DONE

$(filename):    $(filename).o
    gcc -o $(filename) $(filename).o

# $@ for the pattern-matched target
# $< for the pattern-matched dependency
%.o:    %.c
    gcc -o $@ -c $<

clean:
    rm *.o $(filename)

gdb

ref

# start
$gdb <executable name>

# show lines
$list
# set breakpoints
$break <source code line number>
# print variable
$print <var name to print>
# set variable's values
$set <var> = <value>
# watch a variable and pause when it is changed
$watch <var>

# run
$run
# continue
$continue
# hit <return> re-executes the last command
$<return>
# qiut
$quit