The following commands are regular Unix commands that tend to be very useful in shell scripting for system administration.
awk or gawk - pattern scanning language
awk performs pattern matching and processing on input file according to the specifications of the awk program in the file program-file-name or the inline program which consists of a list of patterns and actions. The processing cycle is:
There are a wide variety of options (and books describing them) for this programming language.
cat - catenate files and print on standard output.
catenate each file in files (if not files, read from standard input, and output to stout.
cmp - compare two files.
cut - remove sections from each line of files<
date - print the date
echo - display a line of text
expr - evaluate expressions and print the results at standard output
file - determine file type
find - search for files in a directory hierarchy
fmt - simple optimal text formatter
grep - print lines matching a pattern
head - output the first part of files
join - join lines of two files on a common field
paste - merge lines of files
ps - report process status
sed - a Stream EDitor
test - check file types and compare values
tr - translate or delete characters
uniq - remove duplicate lines from a sorted file
which - show the full path of commands.
xargs - build and execute command lines from standard input.