LinuxQuestions.org - [SOLVED] Question about conditional statements.

For bash the answer is basically "yes", but if a block of commands is executed in a subshell, then changes to variables in that block are not communicated back to the parent shell. A parenthesized list explicitly forces execution to a subshell. Commands run in the background are also done in a separate process. A block of commands with its input or output directed through a pipeline also causes those commands to be executed in a subshell, and this is a frequent cause of problems in shell scripts.

Code:

N=0

echo hello world | {

    cat

    N=42  # This will not be seen in the parent shell

}

echo $N    # N still seen as 0 here

The code within an "if ... then ... fi" construct is also a block that could have its I/O pipelined, though doing so is pretty uncommon:

Code:

N=0

echo testing | if [[ $N == 0 ]]; then

    echo "I am here"

    cat

    N=22

fi

echo $N    # Still seen as 0

Without the pipeline, and even with simple (albeit unusual) redirection, the setting of N does occur in the main shell:

Code:

N=0

if [[ $N == 0 ]]; then

    echo "I am here"

    head

    N=55

fi </etc/profile

echo $N    # Has value 55