Take a look to the following UNIX commands.
who am i -This command shows your user name,teletype,date and time.
whoami – Shows only user name.
In UNIX systems,
parent directory is denoted by ‘..’
current directory is denoted by ‘.’
rmdir – for remove a directory. It removes only empty directories.
About shell :
When we type the commands it goes to the shell.It is an ordinary program.
cat c* //prints all file that begins with c.
when * occurs shell takes it and it means any string of characters. Note the * is not the property of the cat command.
The echo command lists what we type.
echo ch* //lists all begin wth ch.
echo * //lists all.
rm * – removes all.
rm *.text – removes all with .text.
pr r* // prints all that begin wth r and followed by 1,2,3 or 4.
rm te[a-z] //removes all files starting with te and followed by a lower case.
You cannot make up new files using pattern matching.
ls \? or ls ‘?’ loses its meaning.
echo * // prints all.
We can redirect the output by using ‘>’. Take input from a file by using ‘>’.
ls > filelist
pr -3 <filelist // print ls in three columns.
cat file1.c file2.c > file3
cat file4.c >> file3.c
grep num.c <filelist