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+# csv.sh
+
+parse CSV files with pure POSIX shell!
+
+## the short way
+
+(see `csv-min.sh`)
+
+to convert from csv to tab-separated strings:
+
+```
+LC_ALL=C sed -n 's/'"$(printf "\r")"'$//;s/\\/\\\\/g;s/'"$(printf "\t")"'/\\t/g;H;x;h;s/^\n//;s/\n/\\n/g;s/,/,,/g;s/$/,/;s/^/,/;s/,\([^",]*\("[^"]*\(""[^"]*\)*"[^",]*\)*\),/\1'"$(printf "\t")"'/g;/,$/d;s/.$//;s/,,/,/g;s/"\([^"]*\(""[^"]*\)*\)"/\1/g;s/""/"/g;p;s/.*//;h'
+```
+
+tabs, newlines, and backslashes are escaped into `\t`, `\n`, and `\\`, respectively.
+
+to convert back to CSV:
+
+```
+LC_ALL=C sed 's/"/""/g;s/'"$(printf "\t")"'/","/g;s/^/"/;s/$/"/;s/\\\\/& /g;s/\\n/\n/g;s/\\t/'"$(printf "\t")"'/g;s/\\\\ /\\/g;'
+```
+
+(this program doesn't output CR LFs, but you can modify it to! `sed 's/$/'"$(printf "\r")"'/'`)
+
+## what?
+
+see `csv.sh`.
+
+## disclaimer
+
+you shouldn't trust yourself to verify a CSV parser, let alone trust me to write one!
+
+CSV is an amalgamation of formats, loosely described by [RFC 4180](https://www.rfc-editor.org/rfc/rfc4180). i try to be slightly more lenient than RFC 4180, and i tried my parser on output from a variety of programs, but i don't guarantee correctness for weird files.
+
+## license
+
+made by [Natalia Posting](https://equa.space/) in 2023.
+
+Permission to use, copy, modify, and/or distribute this software for
+any purpose with or without fee is hereby granted.
+
+THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL
+WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
+OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE
+FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY
+DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
+AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
+OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.