Sponsored Content
Top Forums UNIX for Advanced & Expert Users Redirection? (I do find some of the strangest things.) Post 302989217 by RudiC on Tuesday 10th of January 2017 05:06:14 AM
Old 01-10-2017
Hmmm, quite some questions in one post. And, I can't comment for all thoses OSes nor all shells, nor on shellcheck. For bash on linux and FreeBSD,
- You can have any number of redirections in a command line any place; they're evaluated left to right, and the last one will be effective. Check what >/tmp/1 cat file1 > /tmp/2 > /tmp/3 does.
- In your line > /dev/null 2>&1 cat /tmp/noise.raw > /dev/dsp it might be interesting to check where the error msgs go. What be your first guess?
- You don't need a command nor a NOP; >/tmp/1 will just open the file, empty it, and close it. This can be (and is) used to effectively create an empty file.
- That shellcheck comment seems to be a warning, not an error. shells allow for that construct.
- Your conclusion about non-existence of /dev/dsp from the permission error might be incorrect.
 

6 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

i get the strangest feeling that lilo hates me.

i need to get rid of lilo's splash screen. i've heard that you can edit your /etc/lilo.conf and add this line: <b>append="splash=0"</b> anyway, i did that and i still have a splash screen. any idea why that didn't work, or what is another way to disable the splash screen? okay, -nydel (1 Reply)
Discussion started by: nydel
1 Replies

2. Programming

Complicating things?

So basically what im trying to do is ... Open file, read that file, than try to find .. We or we and replace them with I, but not replace the cases where words contain We or we, such as Went, went, etc a and replace them with the, but not replace the cases where words contain a, such as... (1 Reply)
Discussion started by: bconnor
1 Replies

3. Programming

Question about several things in C

Hey guys, first of all I'd like to say Hi to everyone. I am new here and this is my first post. I have a question about some C stuff. I am in Computer Science and I have an assignment for a UNIX Applications course. It is really complicated, however. We're using the C language for this and... (1 Reply)
Discussion started by: V4D3R
1 Replies

4. UNIX for Advanced & Expert Users

shell redirection in find

hi, i need to clear data off a DOA backup drive. i try this, but just get a file {} in . and no change on the backup drive. bash shell find /mnt/usbbackup -xdev -type f -exec echo `date` > {} \; any ideas? thanks. :) (1 Reply)
Discussion started by: drewnichols
1 Replies

5. UNIX for Dummies Questions & Answers

Just trying to find out a few things ....

Hi everyone Just a couple of quick questions if I may. Can I ask what is meant by "flavours"?? I've come across it many times in the forums and I'm guessing that it is a variery of either Linux or UNIX (I know nil about either) which has developed but not really got a clue. ... (1 Reply)
Discussion started by: Tiramisu
1 Replies

6. Shell Programming and Scripting

Several exec on find send all the output to the last redirection

Example script: find mydir -type f -exec echo {}>aaa \; -exec echo {}>bbb \;The two paths go the the bbb file, while there should be one of them on each file. How should I do it to get it working? (2 Replies)
Discussion started by: Tribe
2 Replies
MOUNT_UDF(8)						    BSD System Manager's Manual 					      MOUNT_UDF(8)

NAME
mount_udf -- mount a UDF filesystem SYNOPSIS
mount_udf [-o options] [-s sessionStart] [-n lastRecordedLBA] [-b blockSize] [-p packetSizeInBlocks] [-v verificationPolicy] [-w] devicePath mountPath DESCRIPTION
The mount_udf command attaches the UDF filesystem residing on the device devicePath to the global filesystem namespace at the location indi- cated by mountPath. This command is normally executed by mount(8) at boot time. The options are as follows: -o options Options are specified with a -o flag followed by a comma separated string of options. See the mount(8) man page for possible options and their meanings. -v verificationPolicy This is an advanced option not useful for regular use. It controlls the verification policy when writing to RW type optical media. Its value can be "meta", "all", or "none". Policy "meta" means only the metadata are verified after they are written. This is the default policy. Policy "all" means to verify data written, which could be several times slower than policy "meta". Policy "none" does not verify any data. It is only slightly faster than "meta" in normal cases, but may result a corrupted UDF disc if the write of metadata fails. -s sessionStart This is an advanced option not useful for regular use. When manually mounting a UDF volume with Virtual Partition, it specifies the start Logical Block Address of the last session where UDF data structures (VRS and AVDP) resides. This value overrides the value obtained from the device. -n lastRecordedLBA This is an advanced option not useful for regular use. When manually mounting a UDF volume with Virtual Partition, it specifies the last recorded Logical Block Address where the UDF VAT ICB will be searched. This value overrides the value obtained from the device. -b blockSize This is an advanced option not useful for regular use. It specifies the block size in bytes used when mounting the UDF volume. This value overrides the value obtained from the device. -p packetSizeInBlocks This is an advanced option not useful for regular use. It specifies the packet size in blocks when manually mounting the UDF volume. This value overrides the value obtained from the device. -w This is an advanced option not useful for regular use. It forces to enable the experimental packet writing function on optical media that has not been fully supported, such as CD-R, CD-RW, DVD-R, DVD+R, HD DVD-R, and BD-R. Writing to these media does not work on some drives and may cause data corruption or data loss on some other drives. Therefore, this flag should be used only by file system developers when debugging the experimental write functions. The -s, -n, -b, and -p flags are not useful in normal use. They are mainly used for debugging and data recovery. Since the -s, -n, and -p flags are all specified in units of block size, when any of these flags are specified, it is strongly recommended that the -b flag is also specified. SEE ALSO
mount(2), unmount(2), fstab(5), mount(8) BUGS
Reading of all UDF revisions (1.02 - 2.60) on both block device (e.g., hard drives and USB drives) and most optical media is supported. Writing to block devices, DVD-RW and DVD+RW is supported with the following exceptions: (1) Cannot write Finder Info, Resource Fork, or other extended attributes in UDF volumes of revision 1.02 and 1.50; (2) Cannot write to mirrored metadata partition. HISTORY
The mount_udf utility first appeared in Mac OS X. 4th Berkeley Distribution December 6, 2006 4th Berkeley Distribution
All times are GMT -4. The time now is 08:30 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy