Linux Quick-Ref

things I always forget last update 21-jan-08

config xwindows

XF86Setup

/etc/XF86Config config file

kernel compiling

cd /usr/src/linux

make xconfig or menuconfig, config

make clean (cp fl.35 fl.o)

make dep

make zImage or zdisk or bzImage

... (modules, modules_install)

make mrproper deletes zImage...

modify Kernel image

rdev zImage /dev/fd0 set root device

rdev -r zImage 32768

value = bit 0-10 Offset in 1024 bytes of ramdisk

bit 14 load ramdisk

bit 15 prompt before loading root file system

make file system

mke2fs -m 0 /dev/fd0 create ext2 file system on floppy disk

mount

mount -t ext2 /dev/fd0 /mnt/floppy

umount /mnt/floppy

mount -t proc proc /proc mount proc file system

mount -o remount,ro / remount root as readonly

loopdevice

insmod loop.o

dd if=/dev/fd0 of=fdisk.img make floppy-disk image

losetup /dev/loop0 fdisk.img link fdisk.img to /dev/loop0

mount -t msdos /dev/loop0 /mnt/loop mount image

dd if=/dev/zero of=file.img bs=1k count=360 make ext2 image

mke2fs -m 0 file.img create fs on it

mount -o loop file.img /mnt/loop mount it

rmmod loop.o

check dependencies

ldd /bin/execute show dependencies

file /lib/libname lib loader (Qmagic=a.out=ld.so, ELF=ld-linux.so)

nm -C -u -g fname show symbols of lib obj bin (undefined gexternals)

copy

cp -a src1 src2 dstfiles

cp -arv /src/* /dstdir (recursive verbose)

objcopy --strip-all xsrc xdest strip xecutes

objcopy --strip-debug lsrc ldeststripedexe

link

ln src hardlink points to physical place

ln -s src softlink points to src path

ln -s /proc/self/fd0 /dev/stdin

ln -s /proc/self/fd1 /dev/stdout

ln -s /proc/self/fd2 /dev/stderr

manpage

man cmd/fie

apropos keyword

printing

man -t mount | lpr -Pps manpage printing

enscript textfile

dir list

ls -al show all long

ls -ltru list last uaccess time revers order

ps x x also shows deamons

dump

cat /dev/vcs1 screendump tty1

dmesg dump kernel messages

find

find / -iname fnam* find filename ignore case, start in /

grep -i -n string fnam* find string in files / ignore case

compare

diff file1 file2

comm -3 file1 file2 compare file1 - file2 3show differance

diff -Naur olddir newdir >name.patch

cd oldir; patch -p1 < name.patch

diff -U2 -r -N olddir newdir >pathfile.diff

patch -p1 -d destdir < patchfile.diff p1 strip leading dir

compressing

gzip -v9 -c f1 f2 >file.gz compress file f1 f2

gzip -v9 -c f3 >>file.gz add file f3

gzip -l -c file.gz -d (decompress)

tar -tzf file.tgz list files/dir compr file z=gzip j=bzip2

tar -czvf file.tgz dir/* compress dir

tar -xzvpf file.tgz dir extract dir verbose

zcat < file.tgz | star extract

bunzip2 file

Shell scripts (ash)

#!/bin/sh

. /path/take_commands_from_this_file

cd() { command cd $@; PS1="`pwd`# "; }

cmd >file_stdout

cmd 2>file_stderr

VAR=`cat /file`

[ $VAR = 12 ] && only_if_true

[ $VAR = 12 ] || only_if_false

if test -x cmd; then exec cmd

else echo -n cmd not executable

for $ITEM in "A B C"; do list; done

while exp; do list; break; continue; done

case "AL AB CD" in

A|B) list;;

C?) list;;

esac

Linux Boot

lilo / loadlin -> decompress & start kernel

mount root device (decompress rootimg.gz)

/linuxrc

/sbin/init-> /etc/inittab -> /etc/rc.. -> getty -> login -> sh -> profile(s)

lilo.conf

boot=/dev/fd0

install=/boot/boob.b

map=/boot/map

read-write

compact

prompt

image=/zImage

label=Linux

root=/dev/fd0

lilo installlilo -v -C lilo.conf -r /mnt/floppy

loadlin.exe zImage initrd=fdroot.gz root=/dev/ram

Linux Network config

ifconfig lo inet 127.0.0.1 netmask 255.0.0.0

ifconfig eth0 inet 204.204.204.13 netmask 255.255.255.0

route add -net 127.0.0.0 netmask 255.0.0.0 dev lo

route add -net 204.204.204.0 netmaks 255.255.255.0 dev eth0

route add default gw 204.204.204.100

/etc/hosts

ip.ip.ip.adr fqhostname.domain.where alias nickname

/etc/resolf.conf

DNS1

DNS2

Linux GCC

compiling

gcc -m386 -O2 -Wall -o execname src1.cc src2.cc

-o execname (a.out) -c compile only

-O0 no optimalisation -S generate asm source -fverbose-asm

-g enable debugging -l libname

default file ext src.c src.cc asm.s obj.o arch.a lib.a

debugging

gdb execname -tty=/dev/tty8

run arguments ctrl-c

list fie break

next step continue finish

print varname set varname=value

backtrace quit print /x

gdb execname core (coredump)

gproff execname gmon.out (compile with option -pg)

Makefile

LDFLAGS=

LIBRARIES=

CC= gcc

CFLAGS= -Wall -m386 -o2

mySRC= src1.c src2.c

OBJECTS= $(patsubst %.c, %.o, $(mySRC))

all: execname $(LINKS)

execname: $(OBJECTS)

$(CC) $(CFLAGS) $(LDFLAGS) -o execname $(OBJECTS) $(LIBRARIES)

objcopy --strip -all execname execstrip

clean:

- rm -f $(OBJECTS) *~