value. If it doesn't exist or is null, print the error message. If no error message is given, print parameter null or not set. Note: In a non-interactive shell... mnemonic device: # matches the front because number signs precede numbers; % matches the rear because percent signs follow numbers.
The expression ${DIRSTA... the output. Note that basename and dirname don't verify that these parameters are valid filenames or paths. They simple perform simple string operations on a single argument... at work in csh work the same way in bash").
However, buried in there is a section on Parameter Substitution which tells us that $foo is really a
comparisons ===
<code>
#!/bin/bash
a=4
b=5
# Here "a" and "b" can be treated either as integers or strings.
# There is some blurring between th... Bash variables are not strongly typed.
# Bash permits integer operations and comparisons on variables
#+ whose value consists of all-integer characters.
# Caution advised, however.
echo
if [ "$a" -... # This works fine.
# The [ ... ] test operator alone detects whether the string is null.
# However it is good practice
