shell-fu

Tip #850: Checksum directory recursively

Mon, 29 Jun 2009 15:35:41 +0000

Do a sha256sum of an entire directory name directory and check for integrity.
Modifying the IFS variable is necessary for filename with space.

$ IFS='
'
$ for i in $(find directory -type f -print);do sha256sum "$i";done > directory.SHA256SUM
$ sha256sum -c directory.SHA256SUM

Tip #846: Replace expr by other recursively

Tue, 23 Jun 2009 13:22:42 +0000

find . -name *whatyouwant* -exec perl -pi.bak -e 's/toto/foo/g' {} \;

Replace toto by foo in all file found by find.
It make a backup $file.bak

Tip #844: Hide files in an image

Mon, 22 Jun 2009 12:33:46 +0000

It is possible to hide a rar archive inside a png image file and then retrieve the files from this image.

cat picture.png archive.rar > hidden_archive_in_pic.png

This can also be done on Windows:

copy picture.png + archive.rar hidden_archive_in_pic.png

When you want to retrieve the hidden files, download the image, rename to .rar and extract.

Tip #843: Backup delicious bookmarks

Fri, 19 Jun 2009 10:26:15 +0000

Use this command to backup your del.icio.us bookmarks from the commandline with curl.

curl -u username -o bookmarks.xml https://api.del.icio.us/v1/posts/all

Or, using wget

wget --user=username --password=password https://api.del.icio.us/v1/posts/all -O bookmarks.xml

Tip #840: Making vim oneliners

Thu, 18 Jun 2009 12:18:03 +0000

We can use vim to make changes to a file all in one command, for example

vim -c "5,10s/a/b/g | wq" filename

This will open the file 'filename' and replace all occurances of 'a' with 'b' on lines 5-10. The file will then be written and closed. To edit the file after the change, just remove the ' | wq' from the end of the command.

Tip #839: Shutdown a windows PC from linux

Wed, 17 Jun 2009 11:08:52 +0000

A remote Windows PC can easily be shutdown, assuming you have Samba installed on your Linux box, and you have a user account on the Windows PC that has the necessary rights.

Just enter the following command, where 'thehostname' is the hostname of the remote PC, and 'theusername' is a valid user account on the remote PC:

net rpc shutdown -S thehostname -U theusername

If the hostname is not known, or cannot be resolved, then use the following instead, replacing '111.111.111.111' with the IP address of the remote PC:

net rpc shutdown -I 111.111.111.111 -U theusername

Additionally, the parameters that can be used with Windows' own shutdown command such as '-f' to force or '-t' to set a timeout, can also be applied to the net rpc shutdown command as well. For example the following will wait 60 seconds, and then force all running programs to terminate before shutting down:

net rpc shutdown -S thehostname -U theusername -f -t 60

Tip #838: Record a screencast as an mpeg

Tue, 16 Jun 2009 10:36:58 +0000

Use the command below to record a screencast and save it as an mpeg:

ffmpeg -f x11grab -s 800x600 -i :0.0 /tmp/screencast.mpg

Tip #837: Move a file and link to the new location

Mon, 15 Jun 2009 09:33:00 +0000

Use the one liner below to relocate a file or directory, but keep it accessible on the old location through a symlink.

lmv() { [ -e "$1" -a -d "$2" ] && mv "$1" "$2"/ && ln -s "$2"/"$(basename "$1")" "$(dirname "$1")"; }

Tip #836: Find symbolic links

Fri, 12 Jun 2009 12:19:21 +0000

Use this command to find all the links in the current directory and below

find . -lname "*"

Tip #835: Quickly empty a file in vi

Thu, 11 Jun 2009 11:51:27 +0000

A few quick ways to empty a file of text in vi (all of these are done in command mode):

:1,$d
--
:1[enter]dG
--
ggdG