Utilities and Useful Information#

Tab completion#

Pressing Tab will attempt to autocomplete the command/filename/directory you are typing.

$ ls long_file

Then press Tab

$ ls long_file_name_you_cant_remember.txt

history#

Bash will retain a history of the previous commands you entered. The history command will (by default on Palmetto) display the last 1000 commands.

$ history

You can use the up arrow ↑ and down arrow ↓ to scroll through previous commands.

!! will run the previous command.

$ ls
...

$ !!
ls
...

!name will run the last command that started with name.

$ qsub myjob.pbs
...

$ !qsub
qsub myjob.pbs
...

Download Files from the Web#

wget is a useful utility to download files from websites.

$ wget https://github.com/lammps/lammps/archive/refs/tags/stable_23Jun2022_update2.tar.gz

Compressing Files and Directories#

gzip#

gzip file will compress a file to file.gz. Uncompress with gunzip file.gz.

tar#

tar can be used to create a (tape) archive of files/folders.

$ tar czvf my_archive.tar.gz file1 [file2] [directory]

  • -c create archive

  • -z compress (with gzip)

  • -v verbose (print files being placed in the archive)

  • -f use archive name provided (my_archive.tar.gz)

$ tar xzvf my_archive.tar.gz

  • -x extract archive

  • -z uncompress (with gzip)

  • -v verbose (print files being extracted)

  • -f use archive name provided (my_archive.tar.gz)

Convert a Windows file to Unix format#

Copying a file from a Windows computer can cause issues since Windows editors like Notepad will end lines with CRLF line endings. Linux uses the Unix LF line endings.

The dos2unix command will convert the file to Unix format. You can confirm if a file is in the Windows format with file.

$ file copied_from_windows.txt
copied_from_windows.txt: ASCII text, with CRLF line terminators

$ dos2unix copied_from_windows.txt
dos2unix: converting file copied_from_windows.txt to Unix format...

$ file copied_from_windows.txt
copied_from_windows.txt: ASCII text