Tail -n 1 don't work on /proc/curproc/map
If i run tail -n 1 /proc/curproc/map it will print 10 last lines.(wc says it is 11 but something is wrong here)
But then if i redirect output to file and then tail it it will print correct number of lines.
tail -n 1 /proc/curproc/map |wc -l
11 143 1111
tail -n 1 /proc/curproc/map > /tmp/tail-bug && tail -n 1 /tmp/tail-bug |wc
1 13 95
After looking at this issue, it seems that it's because /proc/curproc/map has a size of 0.
In the forward.c code, in that case we're at line 150, calling function rlines : rlines(fp, off, sbp);
But this function starts with a test :
if (!(size = sbp->st_size))
and as the size of the file is 0 it returns immediately and display the whole file instead of the number of lines specified on the cli.
The call of display_lines(fp, off) instead of rlines(fp, off, sbp) seems to fix this issue.