replace stdout line in loop


 
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Old 09-14-2009
replace stdout line in loop

Hi,

as part of a script i have a loop that goes though a set of files.

This loop can take some time, so i'd like to show the user that something is happening by showing them the filename being worked on.

I could create a long list of file names in the terminal using echo or print $filename, but what i'd prefer to do (As the infomation isn't that useful to the user - they'd prefer to easily see the operations prior and after the loop in the terminal) is replace the same stdout line with the current filename in the loop.

I've played around with echo $filename \c, but this just appends all the filenames into a list on the same line (messy). how do i first delete the existing text on the current line so that the user only sees the current filename?

I hope you can make sense of my request!

Nick

---------- Post updated at 12:18 PM ---------- Previous update was at 10:42 AM ----------

solved the issue using 'tput dl1'. to delete the line.
 
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LOSETUP(8)						       System Administration							LOSETUP(8)

NAME
losetup - set up and control loop devices SYNOPSIS
Get info: losetup loopdev losetup -l [-a] losetup -j file [-o offset] Delete loop: losetup -d loopdev... Delete all used loop devices: losetup -D Print name of first unused loop device: losetup -f Setup loop device: losetup [-o offset] [--sizelimit size] [-p pfd] [-rP] {-f[--show]|loopdev} file Resize loop device: losetup -c loopdev DESCRIPTION
losetup is used to associate loop devices with regular files or block devices, to detach loop devices and to query the status of a loop device. If only the loopdev argument is given, the status of the corresponding loop device is shown. Note that the old output format (e.g. losetup -a) with comma delimited strings is deprecated in favour of the --list output format (e.g. losetup -a -l). OPTIONS
+The size and offset arguments may be followed by the multiplicative +suffixes KiB=1024, MiB=1024*1024, and so on for GiB, TiB, PiB, EiB, ZiB and YiB +(the "iB" is optional, e.g. "K" has the same meaning as "KiB") or the suffixes +KB=1000, MB=1000*1000, and so on for GB, TB, PB, EB, ZB and YB. -a, --all show status of all loop devices. Note that not all information are accessible for non-root users. See also --list. The old output format (as printed without --list) is deprecated. -c, --set-capacity loopdev force loop driver to reread size of the file associated with the specified loop device -d, --detach loopdev... detach the file or device associated with the specified loop device(s) -D, --detach-all detach all associated loop devices -f, --find find the first unused loop device. If a file argument is present, use this device. Otherwise, print its name -h, --help print help -j, --associated file show status of all loop devices associated with given file -l, --list if a loop device or the -a option is specified, print default columns for either the specified loop device or all loop devices, default is to print info about all devices. -o, --offset offset the data start is moved offset bytes into the specified file or device -O, --output columns specify which columns are to be printed for the --list output --sizelimit size the data end is set to no more than size bytes after the data start -P, --partscan force kernel to scan partition table on newly created loop device -r, --read-only setup read-only loop device --show print device name if the -f option and a file argument are present. -v, --verbose verbose mode ENCRYPTION
Cryptoloop is no longer supported in favor of dm-crypt. For more details see cryptsetup(8). RETURN VALUE
losetup returns 0 on success, nonzero on failure. When losetup displays the status of a loop device, it returns 1 if the device is not con- figured and 2 if an error occurred which prevented from determining the status of the device. FILES
/dev/loop[0..N] loop block devices /dev/loop-cotrol loop control device EXAMPLE
The following commands can be used as an example of using the loop device. # dd if=/dev/zero of=~/file.img bs=1MiB count=10 # losetup --find --show ~/file.img /dev/loop0 # mkfs -t ext2 /dev/loop0 # mount /dev/loop0 /mnt ... # umount /dev/loop0 # losetup --detach /dev/loop0 AUTHORS
Karel Zak <kzak@redhat.com>, based on original version from Theodore Ts'o <tytso@athena.mit.edu> AVAILABILITY
The losetup command is part of the util-linux package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux/. util-linux July 2003 LOSETUP(8)