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diff --git a/unix/os/doc/zsektx.hlp b/unix/os/doc/zsektx.hlp new file mode 100644 index 00000000..ad9c0020 --- /dev/null +++ b/unix/os/doc/zsektx.hlp @@ -0,0 +1,43 @@ +.help zsektx May84 "System Interface" +.ih +NAME +zsektx -- seek on a text file +.ih +SYNOPSIS +.nf +zsektx (chan, loffset, status) + +int chan # OS channel of text file +long loffset # magic seek offset +int status +.fi +.ih +DESCRIPTION +Text files are normally accessed sequentially, but random access is possible +when reading if \fBzsektx\fR is used to adjust the file position. +The primitive \fBzsektx\fR may be used to set the file position to BOF, EOF, +or to the beginning of any line in the file provided the offset of the line +was determined in a prior call to \fBznottx\fR while reading or writing the +file. +.ih +RETURN VALUE +ERR is returned if there is something wrong with \fIchan\fR or if seeks are +illegal on the device and the seek is to a file position other than BOF or +EOF. If seeks are illegal on the device a request to seek to BOF or EOF is +ignored. OK is returned if the seek is successful. +.ih +NOTES +Depending on the host system, \fIloffset\fR might be a zero indexed byte +offset, the logical record number, the file block number and char offset +within the block packed into a long integer, or some other machine dependent +quantity. The high level code must do nothing with \fIloffset\fR but +request it with \fBznottx\fR and pass the value on to \fBzsektx\fR to perform +a seek. The only way to generate a seek offset for a text file (other than +to BOF or EOF) is to note the file position while reading or writing the file. + +A note followed by a seek while reading or writing a line (newline not yet +seen) rewinds the line. +.ih +SEE ALSO +znottx, zfiotx +.endhelp |