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I just recently decided to skim the GNU Sed manual and it honestly doesn't surprise me one bit that this is possible. Sed is basically a bytecode VM that only d

I just recently decided to skim the GNU Sed manual and it honestly doesn't surprise me one bit that this is possible. Sed is basically a bytecode VM that only does string manipulation.

GPerson 5y ago
Did you acquire any useful new tricks from this experience?
- czx4f4bd 5y ago
  Yeah, it was interesting to learn how sed addresses[0] work, particular regex and range addresses in combination. Basically, you can select a range of lines using regexes. For example, if I wanted to get the text under one header in a Markdown document, I could write something like this: sed -n '/^## Overview/,/^#/ { /^#/b; p }' README.md - The '-n' flag tells sed not to print all matched lines by default. - '/^## Overview/,/^#/' is a range address that matches all lines from one starting with "## Overview" to another line starting with "#", inclusive. - '{ /^#/b; p }' is a command group that's executed for each matched line. - '/^#/b' uses the 'b' (branch) command to skip lines starting with "#" to avoid printing the header lines, which are included in the range. - Finally, 'p' is the print command, which tells sed to print all the other lines. That said, I mainly read it because I've always used things like Bash's built-in parameter expansion[1] and regex capability[2] instead of sed, and I mostly think I confirmed that bias. I'll probably turn to sed for certain string manipulations from now on, but I'm not sure I'll be using it a whole lot more often. [0] https://www.gnu.org/software/sed/manual/sed.html#sed-addresses https://www.gnu.org/software/sed/manual/sed.html#sed-address... [1] https://wiki.bash-hackers.org/syntax/pe https://wiki.bash-hackers.org/syntax/pe [2] https://www.linuxjournal.com/content/bash-regular-expressions https://www.linuxjournal.com/content/bash-regular-expression...
  - GPerson 5y ago
    I didn’t know sed could do that. It seems that vim’s s(ubstitute) utility also has the same features with a near-identical syntax. https://vim.fandom.com/wiki/Search_and_replace https://vim.fandom.com/wiki/Search_and_replace Thanks for sharing!

I just recently decided to skim the GNU Sed manual and it honestly doesn't surprise me one bit that this is possible. Sed is basically a bytecode VM that only does string manipulation.

GPerson 5y ago

Did you acquire any useful new tricks from this experience?

czx4f4bd 5y ago
Yeah, it was interesting to learn how sed addresses[0] work, particular regex and range addresses in combination. Basically, you can select a range of lines using regexes. For example, if I wanted to get the text under one header in a Markdown document, I could write something like this: sed -n '/^## Overview/,/^#/ { /^#/b; p }' README.md - The '-n' flag tells sed not to print all matched lines by default. - '/^## Overview/,/^#/' is a range address that matches all lines from one starting with "## Overview" to another line starting with "#", inclusive. - '{ /^#/b; p }' is a command group that's executed for each matched line. - '/^#/b' uses the 'b' (branch) command to skip lines starting with "#" to avoid printing the header lines, which are included in the range. - Finally, 'p' is the print command, which tells sed to print all the other lines. That said, I mainly read it because I've always used things like Bash's built-in parameter expansion[1] and regex capability[2] instead of sed, and I mostly think I confirmed that bias. I'll probably turn to sed for certain string manipulations from now on, but I'm not sure I'll be using it a whole lot more often. [0] https://www.gnu.org/software/sed/manual/sed.html#sed-addresses https://www.gnu.org/software/sed/manual/sed.html#sed-address... [1] https://wiki.bash-hackers.org/syntax/pe https://wiki.bash-hackers.org/syntax/pe [2] https://www.linuxjournal.com/content/bash-regular-expressions https://www.linuxjournal.com/content/bash-regular-expression...
- GPerson 5y ago
  I didn’t know sed could do that. It seems that vim’s s(ubstitute) utility also has the same features with a near-identical syntax. https://vim.fandom.com/wiki/Search_and_replace https://vim.fandom.com/wiki/Search_and_replace Thanks for sharing!