Change time stamp of a file:
touch -t YYYYMMDDhhmm.ss myfile
 
show full time stamp
ls -la --time-style=full-iso myfile

wildcards

? = replace one char
* = replace 0 or x chars
[a-z] = replace one char in the specified range
[abcde] = replace one char of the specified characters
[!a-z] = replace one char NOT in the specified range

tar

Not well known options
t = list
tar tzf salami.tar.gz

zipping the shit out of the files

gzip -c myfile.txt > myfile.txt.gz creates a myfile.txt.gz and does not delete the original myfile.txt
gzip -l myfile.gz lists the content of myfile.gz

decompress with:

• gzip -d
• gunzip
• zcat

bzip2 has usually better compress rate. It uses the same parameters.
decompress with:

• bzip2 -d
• bunzip
• bzcat

cpio

extract files out of archives
cpio -i | --extract = copy in mode; copy from archive in file system
cpio -o | --create = copy out mode; copy files into the archive
cpio -p | --pass-throughno archive, all files of stdin into a dir

backup all ods in home to backup
find /home/ -name *.ods | cpio -pd /backup

-d = creates directories

dd

backup mbr
dd if=/dev/sda of=mbr.backup ibs=512 count=1

file myfile.sh shows the type of the file

expand x.txt > y.txt replace TAB by spaces
nl x.txt cat with line number
uniq x.txt remove duplicates
split -l 11000 -d catalina.out salami_ split catalina.out evere 11000 lines to a file salami_nn (-d is for numeric file number)
cut -f2 tabulator.txt cut columns 2
paste x.txt y.txt merge two files by column
join -j like paste with "sql like" join on a common key
cat x.txt | tr Q P replace Q by P in x.txt
cat x.txt | tr a-z A-Z lower case to upper case
[:lower:] possible as an argument of tr