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Diffstat (limited to 'text_cmds/col/README')
| -rw-r--r-- | text_cmds/col/README | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/text_cmds/col/README b/text_cmds/col/README new file mode 100644 index 0000000..89e4ce4 --- /dev/null +++ b/text_cmds/col/README @@ -0,0 +1,48 @@ +# @(#)README 8.1 (Berkeley) 6/6/93 +# +# $FreeBSD: src/usr.bin/col/README,v 1.2 2001/06/17 04:24:16 mikeh Exp $ + +col - filter out reverse line feeds. + +Options are: + -b do not print any backspaces (last character written is printed) + -f allow half line feeds in output, by default characters between + lines are pushed to the line below + -p force unknown control sequences to be passed through unchanged + -x do not compress spaces into tabs. + -l num keep (at least) num lines in memory, 128 are kept by default + +In the 32V source code to col(1) the default behavior was to NOT compress +spaces into tabs. There was a -h option which caused it to compress spaces +into tabs. There was no -x flag. + +The 32V documentation, however, was consistent with the SVID (actually, V7 +at the time) and documented a -x flag (as defined above) while making no +mention of a -h flag. Just before 4.3BSD went out, CSRG updated the manual +page to reflect the way the code worked. Suspecting that this was probably +the wrong way to go, this version adopts the SVID defaults, and no longer +documents the -h option. + +Known differences between AT&T's col and this one (# is delimiter): + Input AT&T col this col + #\nabc\E7def\n# # def\nabc\r# # def\nabc\n# + #a# ## #a\n# + - last line always ends with at least one \n (or \E9) + #1234567 8\n# #1234567\t8\n# #1234567 8\n# + - single space not expanded to tab + -f #a\E8b\n# #ab\n# # b\E9\ra\n# + - can back up past first line (as far as you want) so you + *can* have a super script on the first line + #\E9_\ba\E8\nb\n# #\n_\bb\ba\n# #\n_\ba\bb\n# + - always print last character written to a position, + AT&T col claims to do this but doesn't. + +If a character is to be placed on a line that has been flushed, a warning +is produced (the AT&T col is silent). The -l flag (not in AT&T col) can +be used to increase the number of lines buffered to avoid the problem. + +General algorithm: a limited number of lines are buffered in a linked +list. When a printable character is read, it is put in the buffer of +the current line along with the column it's supposed to be in. When +a line is flushed, the characters in the line are sorted according to +column and then printed. |