Return to Answer

You will be adding this to your little Bash library. I can almost bet on it! This has the benefit of not adding a newline character to the end of your output, as will happen with echo throwing off your expected output. Moreover, these solutions are reusable, do not require modifying the shell options, can be called in-line with your pipelines, and are posix compliant. This is the best answer, by far. Modify to your liking.

Output tested with od -cb, something some of the other solutions might want to do with their output.

BTW: The correct quantifier is the +, not the *, as you want the replacement to be triggered upon 1 or more whitespace characters!

ltrim (that you can pipe input into)

function ltrim ()
{
    sed -E 's/^[[:space:]]+//'
}

rtrim (that you can pipe input into)

function rtrim ()
{
    sed -E 's/[[:space:]]+$//'
}

trim (the best of both worlds and yes, you can pipe to it)

function trim ()
{
    ltrim | rtrim
}

You will be adding this to your little Bash library. I can almost bet on it! This has the benefit of not adding a newline character to the end of your output, as will happen with echo throwing off your expected output. Moreover, these solutions are reusable, do not require modifying the shell options, can be called in-line with your pipelines, and are posix compliant. This is the best answer, by far. Modify to your liking.

Output tested with od -cb, something some of the other solutions might want to do with their output.

BTW: The correct quantifier is the +, not the *, as you want the replacement to be triggered upon 1 or more whitespace characters!

ltrim (that you can pipe input into)

function ltrim ()
{
    sed -E 's/^[[:space:]]+//'
}

rtrim (that you can pipe input into)

function rtrim ()
{
    sed -E 's/[[:space:]]+$//'
}

trim (the best of both worlds and yes, you can pipe to it)

function trim ()
{
    ltrim | rtrim
}

Update: I have improved this solution to use bash native constructs. The Stream Editor (sed) is not required. You can use shell expansions to achieve what you want, and it works better than the sed solution!

Bash Reference Manual -- Shell Expansions

You will be adding this to your little Bash library. I can almost bet on it! This has the benefit of not adding a newline character to the end of your output, as will happen with echo throwing off your expected output. Moreover, these solutions are reusable, do not require modifying the shell options, can be called in-line with your pipelines, and are posix compliant. This is the best answer, by far. Modify to your liking.

Output tested with od -cb, something some of the other solutions might want to do with their output.

BTW: The correct quantifier is the +, not the *, as you want the replacement to be triggered upon 1 or more whitespace characters!

ltrim (that you can pipe input into)

function ltrim ()
{
    sed -E 's/^[[:space:]]+//'
}

rtrim (that you can pipe input into)

function rtrim ()
{
    sed -E 's/[[:space:]]+$//'
}

trim (the best of both worlds and you can, and yes, you can pipe to it)

function trim ()
{
    ltrim | rtrim
}

You will be adding this to your little Bash library. I can almost bet on it! This has the benefit of not adding a newline character to the end of your output, as will happen with echo throwing off your expected output. Moreover, these solutions are reusable, do not require modifying the shell options, can be called in-line with your pipelines, and are posix compliant. This is the best answer, by far. Modify to your liking.

Output tested with od -cb, something some of the other solutions might want to do with their output.

BTW: The correct quantifier is the +, not the *, as you want the replacement to be triggered upon 1 or more whitespace characters!

ltrim (that you can pipe input into)

function ltrim ()
{
    sed -E 's/^[[:space:]]+//'
}

rtrim (that you can pipe input into)

function rtrim ()
{
    sed -E 's/[[:space:]]+$//'
}

trim (the best of both worlds and yes, you can pipe to it)

function trim ()
{
    ltrim | rtrim
}

You will be adding this to your little Bash library. I can almost bet on it! This has the benefit of not adding a newline character to the end of your output, as will happen with echo throwing off your expected output. Moreover, these solutions are reusable, do not require modifying the shell options, can be called in-line with your pipelines, and are posix compliant. This is the best answer, by far. Modify to your liking.

BTW: The correct quantifier is the +, not the *, as you want the replacement to be triggered upon 1 or more whitespace characters!

ltrim (that you can pipe input into)

function ltrim ()
{
    sed -E 's/^[[:space:]]+//'
}

rtrim (that you can pipe input into)

function rtrim ()
{
    sed -E 's/[[:space:]]+$//'
}

trim (the best of both worlds and you can, and yes, you can pipe to it)

function trim ()
{
    ltrim | rtrim
}

You will be adding this to your little Bash library. I can almost bet on it! This has the benefit of not adding a newline character to the end of your output, as will happen with echo throwing off your expected output. Moreover, these solutions are reusable, do not require modifying the shell options, can be called in-line with your pipelines, and are posix compliant. This is the best answer, by far. Modify to your liking.

Output tested with od -cb, something some of the other solutions might want to do with their output.

BTW: The correct quantifier is the +, not the *, as you want the replacement to be triggered upon 1 or more whitespace characters!

ltrim (that you can pipe input into)

function ltrim ()
{
    sed -E 's/^[[:space:]]+//'
}

rtrim (that you can pipe input into)

function rtrim ()
{
    sed -E 's/[[:space:]]+$//'
}

trim (the best of both worlds and you can, and yes, you can pipe to it)

function trim ()
{
    ltrim | rtrim
}