linux notes ch1, ch2

Date Added: 14/01/2015

ls ,cd , pwd , vi, gedit, cp,mv,rm,pico,touch

history

cat -n (-n line number)

>> or 2> save to file the output

script and scriptreplay command like videoplayer you can record the code uyou write to terminal.

$ script -t 2> timing.log -a output.session
type commands;
…
..
exit

$ scriptreplay timing.log output.session

find /home/muslum -name "*.php" finds php files

-iname ignore case sensitive

-path search path

-regex : $ find . -regex ".*$\.py\|\.sh$$"

using more condition:

new.txt some.jpg text.pdf
$ find . $ -name "*.txt" -o -name "*.pdf" $ -print
./text.pdf
./new.txt

find by file ( access time - time, modification time -mtime , change time -ctime ) -ctime +7 means before 7 day ago

search based on file size

-delete : deleting matched files

serach based on permission (755) and ownership

$ find . -type f -name "*.php" !-perm 644 -print

$ find . -type f -user slynux -print

exec chown username {} changes file owner change can be done by a mathes

serach -prune ignore matches

xargs

output | tr 'find text' 'replace text'

tr -d delete option

For example:
$ echo "Hello 123 world 456" | tr -d '0-9'

Hello world

tr -s

echo "ddddd 432 ddsa dd" | tr -s 'dd '
output : "d432 dsa d"

Checksum and Varification

$ md5deep -rl directory_path > directory.md5
# -r to enable recursive traversal
# -l for using relative path. By default it writes absolute file path in
output
Alternately, use a combination of find to calculate checksums recursively:
$ find directory_path -type f -print0 | xargs -0 md5sum >> directory.md5
To verify, use the following

Cryptographic tool and Hashes

cript , gpg, base64, md5sum, sha1sum, opensslpasswd

Sorting unique and dublicates

commands: sort ,uniq

sorting file content in alpha,numeric,reverse,merge sorted, and unique
sorting according to key and column

# Sort reverse by column1
$ sort -nrk 1 data.txt
4 linux 1000
3 bsd 1000
2 winxp 4000
1 mac 2000
# -nr means numeric and reverse

spliting file and data

you can spli5t files by matches and based on its content data, extension

split ,csplit

$ split [COMMAND_ARGS] PREFIX

$ csplit server.log /SERVER/ -n 2 -s {*} -f server -b "d.log" ; rm
server00.log
$ ls
server01.log server02.log server03.log server.log

based on extension

he name from name.extension can be easily extracted using the % operator. You can
extract the name from "sample.jpg" as follows:
file_jpg="sample.jpg"
name=${file_jpg%.*}
echo File name is: $name
The output is:
File name is: sample
The next task is to extract the extension of a file from its filename. The extension can be
extracted using the # operator as follows:
Extract .jpg from the filename stored in the variable file_jpg as follows:
extension=${file_jpg#*.}
echo Extension is: jpg
The output is:
Extension is: jpg

Rename

Renaming *.JPG to *.jpg:

$ rename *.JPG *.jpg

To replace space in the filenames with the "_" character:
$ rename 's/ /_/g' *
# 's/ /_/g' is the replacement part in the filename and * is the wildcard for the
target files. It can be *.txt or any other wildcard pattern.
To convert any filename of files from uppercase to lowercase and vice versa:
$ rename 'y/A-Z/a-z/' *
$ rename 'y/a-z/A-Z/' *
To recursively move all the .mp3 files to a given directory:
$ find path -type f -name "*.mp3" -exec mv {} target_dir \;
To recursively rename all the files by replacing space with the "_" character:
$ find path -type f -exec rename 's/ /_/g' {} \;