Does grep --color default to =auto or =always?

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What is the default color behavior for grep --color if no [=WHEN] is specified?

The grep man page states:


 --color[=WHEN], --colour[=WHEN]
 Surround the matched (non-empty) strings, matching lines, context lines,
 file names, line numbers, byte offsets, and separators (for fields and
 groups of context lines) with escape sequences to display them in color
 on the terminal.
 ...
 WHEN is never, always, or auto.

Does the default [=WHEN] for grep --color become:

grep --color=auto

grep --color=always

or does it depend on implementation and platform?

In my tests on Ubuntu 14.04 with GNU grep 2.16:

echo "foo bar" | grep --color foo

results in foobar, while

echo "foo bar" | grep --color foo | grep --color bar

results in foobar, so it appears that grep --color=auto is in effect here. I have not tested this on Windows or Mac, however; I don't know if this behavior is universal.

This default for [=WHEN] is a little different from ls --color where the man page for ls states:
--color[=WHEN] colorize the output. WHEN defaults to always or can be never or auto.

Here, the behavior of the missing WHEN is explicit.

edited 6 mins ago

Fabby

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up vote
2
down vote

favorite

What is the default color behavior for grep --color if no [=WHEN] is specified?

The grep man page states:


 --color[=WHEN], --colour[=WHEN]
 Surround the matched (non-empty) strings, matching lines, context lines,
 file names, line numbers, byte offsets, and separators (for fields and
 groups of context lines) with escape sequences to display them in color
 on the terminal.
 ...
 WHEN is never, always, or auto.

Does the default [=WHEN] for grep --color become:

grep --color=auto

grep --color=always

or does it depend on implementation and platform?

In my tests on Ubuntu 14.04 with GNU grep 2.16:

echo "foo bar" | grep --color foo

results in foobar, while

echo "foo bar" | grep --color foo | grep --color bar

results in foobar, so it appears that grep --color=auto is in effect here. I have not tested this on Windows or Mac, however; I don't know if this behavior is universal.

This default for [=WHEN] is a little different from ls --color where the man page for ls states:
--color[=WHEN] colorize the output. WHEN defaults to always or can be never or auto.

Here, the behavior of the missing WHEN is explicit.

edited 6 mins ago

Fabby

2,68411023

asked 52 mins ago

OnlineCop

1163

add a commentÂ |Â

up vote
2
down vote

favorite

What is the default color behavior for grep --color if no [=WHEN] is specified?

The grep man page states:


 --color[=WHEN], --colour[=WHEN]
 Surround the matched (non-empty) strings, matching lines, context lines,
 file names, line numbers, byte offsets, and separators (for fields and
 groups of context lines) with escape sequences to display them in color
 on the terminal.
 ...
 WHEN is never, always, or auto.

Does the default [=WHEN] for grep --color become:

grep --color=auto

grep --color=always

or does it depend on implementation and platform?

In my tests on Ubuntu 14.04 with GNU grep 2.16:

echo "foo bar" | grep --color foo

results in foobar, while

echo "foo bar" | grep --color foo | grep --color bar

results in foobar, so it appears that grep --color=auto is in effect here. I have not tested this on Windows or Mac, however; I don't know if this behavior is universal.

This default for [=WHEN] is a little different from ls --color where the man page for ls states:
--color[=WHEN] colorize the output. WHEN defaults to always or can be never or auto.

Here, the behavior of the missing WHEN is explicit.

edited 6 mins ago

Fabby

2,68411023

asked 52 mins ago

OnlineCop

1163

What is the default color behavior for grep --color if no [=WHEN] is specified?

The grep man page states:


 --color[=WHEN], --colour[=WHEN]
 Surround the matched (non-empty) strings, matching lines, context lines,
 file names, line numbers, byte offsets, and separators (for fields and
 groups of context lines) with escape sequences to display them in color
 on the terminal.
 ...
 WHEN is never, always, or auto.

Does the default [=WHEN] for grep --color become:

grep --color=auto

grep --color=always

or does it depend on implementation and platform?

In my tests on Ubuntu 14.04 with GNU grep 2.16:

echo "foo bar" | grep --color foo

results in foobar, while

echo "foo bar" | grep --color foo | grep --color bar

results in foobar, so it appears that grep --color=auto is in effect here. I have not tested this on Windows or Mac, however; I don't know if this behavior is universal.

This default for [=WHEN] is a little different from ls --color where the man page for ls states:
--color[=WHEN] colorize the output. WHEN defaults to always or can be never or auto.

Here, the behavior of the missing WHEN is explicit.

grep colors

edited 6 mins ago

Fabby

2,68411023

asked 52 mins ago

OnlineCop

1163

edited 6 mins ago

Fabby

2,68411023

asked 52 mins ago

OnlineCop

1163

edited 6 mins ago

Fabby

2,68411023

edited 6 mins ago

Fabby

2,68411023

edited 6 mins ago

Fabby

2,68411023

asked 52 mins ago

OnlineCop

1163

asked 52 mins ago

OnlineCop

1163

asked 52 mins ago

OnlineCop

1163

add a commentÂ |Â

1 Answer
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It defaults to auto.

grep --color is the same as writing --color=auto.

This seems to be deficiently documented, or they consider the simple --color deprecated, but that can be seen both from testing and from its source code:

 case COLOR_OPTION:
 if (optarg)
 !strcasecmp (optarg, "tty")
 
 else
 color_option = 2;
 break;

Notice that the lack of an optarg results in the same as it being equal to auto or tty.

edited 31 mins ago

Stephen Kitt

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answered 40 mins ago

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1 Answer
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oldest

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up vote
5
down vote

It defaults to auto.

grep --color is the same as writing --color=auto.

This seems to be deficiently documented, or they consider the simple --color deprecated, but that can be seen both from testing and from its source code:

 case COLOR_OPTION:
 if (optarg)
 !strcasecmp (optarg, "tty")
 
 else
 color_option = 2;
 break;

Notice that the lack of an optarg results in the same as it being equal to auto or tty.

edited 31 mins ago

Stephen Kitt

154k23340409

answered 40 mins ago

mosvy

3,600119

add a commentÂ |Â

up vote
5
down vote

It defaults to auto.

grep --color is the same as writing --color=auto.

This seems to be deficiently documented, or they consider the simple --color deprecated, but that can be seen both from testing and from its source code:

 case COLOR_OPTION:
 if (optarg)
 !strcasecmp (optarg, "tty")
 
 else
 color_option = 2;
 break;

Notice that the lack of an optarg results in the same as it being equal to auto or tty.

edited 31 mins ago

Stephen Kitt

154k23340409

answered 40 mins ago

mosvy

3,600119

add a commentÂ |Â

up vote
5
down vote

It defaults to auto.

grep --color is the same as writing --color=auto.

This seems to be deficiently documented, or they consider the simple --color deprecated, but that can be seen both from testing and from its source code:

 case COLOR_OPTION:
 if (optarg)
 !strcasecmp (optarg, "tty")
 
 else
 color_option = 2;
 break;

Notice that the lack of an optarg results in the same as it being equal to auto or tty.

edited 31 mins ago

Stephen Kitt

154k23340409

answered 40 mins ago

mosvy

3,600119

It defaults to auto.

grep --color is the same as writing --color=auto.

This seems to be deficiently documented, or they consider the simple --color deprecated, but that can be seen both from testing and from its source code:

 case COLOR_OPTION:
 if (optarg)
 !strcasecmp (optarg, "tty")
 
 else
 color_option = 2;
 break;

Notice that the lack of an optarg results in the same as it being equal to auto or tty.

edited 31 mins ago

Stephen Kitt

154k23340409

answered 40 mins ago

mosvy

3,600119

edited 31 mins ago

Stephen Kitt

154k23340409

edited 31 mins ago

Stephen Kitt

154k23340409

edited 31 mins ago

Stephen Kitt

154k23340409

answered 40 mins ago

mosvy

3,600119

answered 40 mins ago

mosvy

3,600119

answered 40 mins ago

mosvy

3,600119

add a commentÂ |Â

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