grep can grab context by lines (-A LINES for context after, -B LINES for context before, and -C LINES for context both before and after) but it does not have a flag for horizontal context. You can do that with a regex though:

(-E uses Extended Regular Expressions (ERE), allowing for syntax like .{0,10} (match any character zero to ten times).  -o displays only the matched content, one match per line.)

If your version of grep doesn't support -P, you can use perl:

This modifies the regex slightly to include a matching group so we can refer to the matched text later. Otherwise, it's just a loop on each match (the g matches globally rather than just the first time) that then prints the match with a newline.

A final note: A comment to the question used the syntax .{,5} which works in grep -E but almost nowhere else (certainly neither grep -P nor perl). It is a bad habit to use that format rather than explicitly including the zero in .{0,5}.

GNU grep can grab context by lines (-A LINES for context after, -B LINES for context before, and -C LINES for context both before and after) but it does not have a flag for horizontal context. You can do that with a regex though:

(-E uses Extended Regular Expressions (ERE), allowing for syntax like .{0,10} (match any character 0–10 times). GNU grep's -o displays only the matched content, one match per line.)

If your version of grep doesn't support -P or -o, you can use perl:

This modifies the regex slightly to include a matching group so we can refer to the matched text later. Otherwise, it's just a loop on each match (the g matches globally rather than just the first time) that then prints the match with a newline.

GNU vs POSIX grep

GNU grep adds a lot of functionality atop the POSIX standard grep. Specific to this answer, -A LINES (lines of context after), -B LINES (lines of context before), -C LINES (lines of context both before and after), -o (show only the match), and -P (use PCRE) are all available in GNU grep but cannot be assumed for other grep implementations. BSD grep supports all of them except -P, but GNU grep is often preferred by BSD users due to GNU's performance optimizations.

Both GNU and BSD grep commands also support --color, which you could use as an alternative to -o. This will end up showing entire lines with the matching text ("media" plus its 0–10 characters of context) colored.

A final note: A comment to the question used the syntax .{,5}, which works in grep -E but almost nowhere else (certainly neither grep -P nor perl). It is a bad habit to use that format rather than explicitly including the zero in .{0,5}.

grep can grab context by lines (-A LINES for context after, -B LINES for context before, and -C LINES for context both before and after) but it does not have a flag for horizontal context. You can do that with a regex though:

grep -Eo '.{0,10}media.{0,10}'

(-E uses Extended Regular Expressions (ERE), allowing for syntax like .{0,10} (match any character zero to ten times). -o displays only the matched content, one match per line.)

Greediness

Note, this won't be a comprehensive list since some copies of the word "media" may be too close to what is already captured. For example:

$ echo 123 media 123 media 1234567890 media 123 |grep -Eo '.{0,10}media.{0,10}'
123 media 123 media
234567890 media 123

You get all three instances of "media" but since one of them is within ten characters of another, it was already accounted for.

If have GNU grep compiled with libpcre, you can tell those wildcards to be lazy rather than greedy:

$ echo 123 media 123 media 1234567890 media 123 |grep -Po '.{0,10}?media.{0,10}?'
123 media
 123 media
234567890 media

The -P flag enables perl-compatible regular expression (PCRE) evaluation.

The lazy evaluation (also called "non-greedy evaluation") aspires to prevent one match from interfering with another rather than consuming as many of the ten characters as possible, which limits further matches.

If your version of grep doesn't support -P, you can use perl:

$ echo 123 media 123 media 1234567890 media 123 |perl -ne \
    'while (/(.{0,10}?media.{0,10}?)/g) { print "$1\n"; }'
123 media
 123 media
234567890 media

This modifies the regex slightly to include a matching group so we can refer to the matched text later. Otherwise, it's just a loop on each match (the g matches globally rather than just the first time) that then prints the match with a newline.

A final note: A comment to the question used the syntax .{,5} which works in grep -E but almost nowhere else (certainly neither grep -P nor perl). It is a bad habit to use that format rather than explicitly including the zero in .{0,5}.

grep can grab context by lines (-A LINES for context after, -B LINES for context before, and -C LINES for context both before and after) but it does not have a flag for horizontal context. You can do that with a regex though:

grep -Eo '.{0,10}media.{0,10}'

(-E uses Extended Regular Expressions (ERE), allowing for syntax like .{0,10} (match any character zero to ten times). -o displays only the matched content, one match per line.)

Greediness

Note, this won't be a comprehensive list since some copies of the word "media" may be too close to what is already captured. For example:

$ echo 123 media 12345 media 123456789 media 12 |grep -Eo '.{0,10}media.{0,10}'
123 media 12345 med
234567890 media 123

You get parts of all three instances of "media" but since one of them is partially within ten characters of another, only that part of it was represented.

If have GNU grep compiled with libpcre, you can tell those wildcards to be lazy rather than greedy:

$ echo 123 media 12345 media 123456789 media 12 |grep -Po '.{0,10}?media.{0,10}?'
123 media
 12345 media
234567890 media

The -P flag enables Perl-Compatible Regular Expression (PCRE) evaluation.

The lazy evaluation (also called "non-greedy evaluation") aspires to prevent one match from interfering with another rather than consuming as many of the ten characters as possible, which limits further matches.

If your version of grep doesn't support -P, you can use perl:

$ echo 123 media 123 media 123456789 media 12 |perl -ne \
    'while (/(.{0,10}?media.{0,10}?)/g) { print "$1\n"; }'
123 media
 12345 media
234567890 media

This modifies the regex slightly to include a matching group so we can refer to the matched text later. Otherwise, it's just a loop on each match (the g matches globally rather than just the first time) that then prints the match with a newline.

A final note: A comment to the question used the syntax .{,5} which works in grep -E but almost nowhere else (certainly neither grep -P nor perl). It is a bad habit to use that format rather than explicitly including the zero in .{0,5}.