DE
The sed utility shall support the BREs described in the Base Definitions volume of IEEE Std 1003.1-2001, Section 9.3, Basic Regular Expressions, with the following additions:
In a context address, the construction "\cBREc", where c is any character other than backslash or <newline>, shall be identical to "/BRE/". If the character designated by c appears following a backslash, then it shall be considered to be that literal character, which shall not terminate the BRE. For example, in the context address "\xabc\xdefx", the second x stands for itself, so that the BRE is "abcxdef".
The escape sequence '\n' shall match a <newline> embedded in the pattern space. A literal <newline> shall not be used in the BRE of a context address or in the substitute function.
If an RE is empty (that is, no pattern is specified) sed shall behave as if the last RE used in the last command applied (either as an address or as part of a substitute command) was specified.
In a context address, the construction "\cBREc", where c is any character other than backslash or <newline>, shall be identical to "/BRE/". If the character designated by c appears following a backslash, then it shall be considered to be that literal character, which shall not terminate the BRE. For example, in the context address "\xabc\xdefx", the second x stands for itself, so that the BRE is "abcxdef".
The escape sequence '\n' shall match a <newline> embedded in the pattern space. A literal <newline> shall not be used in the BRE of a context address or in the substitute function.
If an RE is empty (that is, no pattern is specified) sed shall behave as if the last RE used in the last command applied (either as an address or as part of a substitute command) was specified.
