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I need head -z for a script (off-topic, but the motivation can be found in this question), but in my CoreOS 835.13.0 I get head: invalid option -- 'z'.

Full head --help output:

Usage: head [OPTION]... [FILE]...
Print the first 10 lines of each FILE to standard output.
With more than one FILE, precede each with a header giving the file name.
With no FILE, or when FILE is -, read standard input.

Mandatory arguments to long options are mandatory for short options too.
  -c, --bytes=[-]K         print the first K bytes of each file;
                             with the leading '-', print all but the last
                             K bytes of each file
  -n, --lines=[-]K         print the first K lines instead of the first 10;
                             with the leading '-', print all but the last
                             K lines of each file
  -q, --quiet, --silent    never print headers giving file names
  -v, --verbose            always print headers giving file names
      --help     display this help and exit
      --version  output version information and exit

K may have a multiplier suffix:
b 512, kB 1000, K 1024, MB 1000*1000, M 1024*1024,
GB 1000*1000*1000, G 1024*1024*1024, and so on for T, P, E, Z, Y.

GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
Report head translation bugs to <http://translationproject.org/team/>
For complete documentation, run: info coreutils 'head invocation'

The funny part is that the last line tells me to run info coreutils 'head invocation' but I get info: command not found.

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Swap NULs and NLs before and after head:

<file tr '\0\n' '\n\0' | head | tr '\n\0' '\0\n'

With recent versions of GNU sed:

sed -z 10q

With GNU awk:

gawk -v RS='\0' -v ORS='\0' '{print}; NR == 10 {exit}'

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