1# @(#)README 8.1 (Berkeley) 6/6/93 2# 3 4col - filter out reverse line feeds. 5 6Options are: 7 -b do not print any backspaces (last character written is printed) 8 -f allow half line feeds in output, by default characters between 9 lines are pushed to the line below 10 -p force unknown control sequences to be passed through unchanged 11 -x do not compress spaces into tabs. 12 -l num keep (at least) num lines in memory, 128 are kept by default 13 14In the 32V source code to col(1) the default behavior was to NOT compress 15spaces into tabs. There was a -h option which caused it to compress spaces 16into tabs. There was no -x flag. 17 18The 32V documentation, however, was consistent with the SVID (actually, V7 19at the time) and documented a -x flag (as defined above) while making no 20mention of a -h flag. Just before 4.3BSD went out, CSRG updated the manual 21page to reflect the way the code worked. Suspecting that this was probably 22the wrong way to go, this version adopts the SVID defaults, and no longer 23documents the -h option. 24 25Known differences between AT&T's col and this one (# is delimiter): 26 Input AT&T col this col 27 #\nabc\E7def\n# # def\nabc\r# # def\nabc\n# 28 #a# ## #a\n# 29 - last line always ends with at least one \n (or \E9) 30 #1234567 8\n# #1234567\t8\n# #1234567 8\n# 31 - single space not expanded to tab 32 -f #a\E8b\n# #ab\n# # b\E9\ra\n# 33 - can back up past first line (as far as you want) so you 34 *can* have a super script on the first line 35 #\E9_\ba\E8\nb\n# #\n_\bb\ba\n# #\n_\ba\bb\n# 36 - always print last character written to a position, 37 AT&T col claims to do this but doesn't. 38 39If a character is to be placed on a line that has been flushed, a warning 40is produced (the AT&T col is silent). The -l flag (not in AT&T col) can 41be used to increase the number of lines buffered to avoid the problem. 42 43General algorithm: a limited number of lines are buffered in a linked 44list. When a printable character is read, it is put in the buffer of 45the current line along with the column it's supposed to be in. When 46a line is flushed, the characters in the line are sorted according to 47column and then printed. 48