Shell Programming and Scripting

@elixir_sinari
woow.... thank you so much for the explanation...
btw, i have a problem with variable assigning:

Code:

last_day=$(cal | tr ' ' '\n'|grep -v '^$' |tail -1)

when I wrote codes above directly (not in script), there is an error after I entered the code, it says that syntax error: `last_days=$' unexpected. What is the correct syntax to assigning variable in bourne shell?

Use backticks in the original Bourne Shell.

Code:

last_day=`cal | tr ' ' '\n'|grep -v '^$' |tail -1`

All modern unix and Linux systems come with something better than the old Bourne Shell.
Solaris is unusual in that /usr/bin/sh is the old Bourne Shell. The $( ) syntax is valid in Korn Shell (/usr/bin/ksh) and the Posix Shell (/usr/xpg4/bin/sh).

Though I have never seen a version of cal where the default output is two months, the syntax for the current month would be:

Code:

cal $(date +'%m %Y')
or
cal `date +'%m %Y'`