On Sun, 6 Jan 2019 21:19:50, Corinna Vinschen wrote: > > On Dec 16 17:31, Houder wrote: > > L.S., > > > > /dev/fd/N not synonymous with file descriptor N; it is on Linux > > > > 64-@@ cat /dev/fd/0 <<\EOF > > > Hi > > > EOF > > cat: /dev/fd/0: No such file or directory > > > > fails on Cygwin; not on Linux. > > > > Also see: > > > > https://cygwin.com/ml/cygwin/2018-12/msg00028.html > > ( Bash heredoc on FD 3 ) > > > > Based on the output of strace on Linux, I composed an STC, that duplicates > > the steps taken by bash (and cat). > > This should work in the latest developer snapshot uploaded to > https://cygwin.com/snapshots/ Please give it a try. > > Thanks, > Corinna
Nice! This solves: <program> -i /dev/fd/N N<<EOF (i.e. Steven Penny's problem) Howver ... (and I sure that I am not telling you anything new) it still not the same as Linux ... So, for the record only: - suppose a hacker deletes the logfile, but the file is still "help open" by some program - the logfile can be rescued on Linux, but not on Cygwin 64-@@ echo aap > aap.txt 64-@@ tail -f aap.txt aap .. in another terminal 64-@@ ls -l /proc/4120/fd # 4120 is the procid of "tail" total 0 lrwxrwxrwx 1 Henri None 0 Jan 22 09:25 0 -> /dev/pty1 lrwxrwxrwx 1 Henri None 0 Jan 22 09:25 1 -> /dev/pty1 lrwxrwxrwx 1 Henri None 0 Jan 22 09:25 2 -> /dev/pty1 lrwxrwxrwx 1 Henri None 0 Jan 22 09:25 3 -> /home/Henri/redirect/aap.txt 64-@@ stat -L /proc/4120/fd/3 # shows a file of 4 bytes ... File: /proc/4120/fd/3 Size: 4 Blocks: 1 IO Block: 65536 regular file Device: 33d91880h/869865600d Inode: 35747322042382612 Links: 1 Access: (0644/-rw-r--r--) Uid: ( 1000/ Henri) Gid: ( 513/ None) Access: 2019-01-22 09:24:41.978178200 +0100 Modify: 2019-01-22 09:24:41.978178200 +0100 Change: 2019-01-22 09:24:41.978178200 +0100 Birth: 2019-01-22 09:24:41.978178200 +0100 64-@@ rm aap.txt # hacker removing the logfile 64-@@ stat -L /proc/4120/fd/3 File: /proc/4120/fd/3 Size: 4 Blocks: 1 IO Block: 65536 regular file Device: 33d91880h/869865600d Inode: 35747322042382612 Links: 0 Access: (0644/-rw-r--r--) Uid: ( 1000/ Henri) Gid: ( 513/ None) Access: 2019-01-22 09:24:41.978178200 +0100 Modify: 2019-01-22 09:24:41.978178200 +0100 Change: 2019-01-22 09:26:25.021040800 +0100 Birth: 2019-01-22 09:24:41.978178200 +0100 64-@@ cp /proc/4120/fd/3 noot.txt # logfile rescue 64-@@ cat noot.txt # empty! (however, this works on Linux) 64-@@ cat /proc/4120/fd/3 # indeed, does not show contents 64-@@ ===== -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
