/usr/bin/ed

GNU ed is a line-oriented text editor. It is used to create, display,
modify and otherwise manipulate text files, both interactively and via
shell scripts. A restricted version of ed, red, can only edit files in
the current directory and cannot execute shell commands. Ed is the
'standard' text editor in the sense that it is the original editor for
Unix, and thus widely available. For most purposes, however, it is
superseded by full-screen editors.

Usage: /usr/bin/ed [options] [[+line] file]

The file name may be preceded by '+line', '+/RE', or '+?RE' to set the
current line to the line number specified or to the first or last line
matching the regular expression 'RE'.

Start edit by reading in 'file' if given.
If 'file' begins with a '!', read output of shell command.

The environment variable LINES can be used to set the initial window size.

Options:
  -h, --help                 display this help and exit
  -V, --version              output version information and exit
  -E, --extended-regexp      use extended regular expressions
  -G, --traditional          run in compatibility mode
  -l, --loose-exit-status    exit with 0 status even if a command fails
  -p, --prompt=STRING        use STRING as an interactive prompt
  -q, --quiet, --silent      suppress diagnostics written to stderr
  -r, --restricted           run in restricted mode
  -s, --script               suppress byte counts and '!' prompt
  -v, --verbose              be verbose; equivalent to the 'H' command
      --strip-trailing-cr    strip carriage returns at end of text lines
      --unsafe-names         allow control characters in file names

*Exit status*
0 for a normal exit, 1 for environmental problems (invalid command-line
options, memory exhausted, command failed, etc), 2 for problems with the
input file (file not found, buffer modified, I/O errors), 3 for an internal
consistency error (e.g., bug) which caused ed to panic.

*See also*
regex(7)

Report bugs to bug-ed@gnu.org
Ed home page: http://www.gnu.org/software/ed/ed.html
General help using GNU software: http://www.gnu.org/gethelp