Useful Linux Commands

• Count
• Transfer Files
• Print info
• Download
• Screen
• Ctags
• nohup
• Others

Count

Count lines in a document

$ wc -l /dir/file.txt

$ cat /dir/file.txt | wc -l

Filter and count only lines with pattern, or with -v to invert match

$ grep -w "pattern" -c file

$ grep -w "pattern" -c -v file

Count files in the current directory:

$ ls -l | grep “^-” | wc -l

example: counting all js files in directory “/home/account/” (recursively):

$ ls -lR /home/account | grep js | wc -l

$ ls -l "/home/account" | grep "js" | wc -l

Count files in the current directory, recursively:

$ ls -lR | grep “^-” | wc -l

Count folders in the current directory, recursively:

$ ls -lR | grep “^d” | wc -l

Transfer Files

Remote transfer files, remote -> local:

$ scp account@111.111.111.111:/path/to/remote/file /path/to/local/

Remote transfer files, local -> remote:

$ scp /path/to/local/file account@111.111.111.111:/path/to/remote/

Print directory structure:

$ ls -l -R

Print folder in current directory:

$ ls -lF |grep /

$ ls -l |grep '^d'

Print history command:

$ history

$ history | less

Print info

Print system info:

$ cat /proc/version

Print software info:

$ whereis SOFEWARE
$ which SOFEWARE
$ locate SOFEWARE

Print CPU info:

$ cat /proc/cpuinfo

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Print memory info:

$ cat /proc/meminfo

$ free -m

Print graphics card version:

$ nvcc --version

Print graphics card GPU info:

$ nvidia-smi

Print disk free space:

$ df -h
$ df -hl

Print current folder size

$ du -sh DIRNAME

Print target folder volume (in MB)

$ du -sm

Download

Download file:

$ wget "http://domain.com/directory/4?action=AttachFile&do=view&target=file.tgz"

Download file to specific directory:

$ wget -O /home/omio/Desktop/ "http://thecanadiantestbox.x10.mx/CC.zip"

Download all files from a folder on a website or FTP:

$ wget -r --no-parent --reject "index.html*" http://vision.cs.utexas.edu/voc/

Perl-based rename commands(-n: test commands; -v: print renamed files):

$ rename -n 's/\.htm$/\.html/' \*.htm

$ rename -v 's/\.htm$/\.html/' \*.htm

Screen

Run program in screen mode:

$ screen python demo.py --gpu 1

Detach screen: Ctrl + a, c

Re-connect screen:

$ screen -r pid

Display all screens:

$ screen -ls

Delete screen:

$ kill pid

Naming a screen:

$ screen -S sessionName

Ctags

ctags –R * : Generate tags files in source code root directory

vim -t func/var: find func/var definition

:ts: give a list if func/var has multiple definitions

Ctrl+]: jump to definition

Ctrl+T: jump back

nohup

$ nohup command-with-options &

$ nohup xxx.sh 1 > log.txt 2>&1 &

nohup - get the process ID to kill a nohup process

$ nohup command-with-options &

$ echo $! > save_pid.txt

$ kill -9 `cat save_pid.txt`

Others

Launch terminal in Ubuntu: Ctrl+Alt+T

Create symbol link:

$ ln -s EXISTING_FILE SYMLINK_FILE
$ ln -s /path/to/file /path/to/symlink

Open image:

$ eog /path/to/image/im.jpg

$ display /path/to/image/im.jpg

Convert text files with DOS or MAC line breaks to Unix line breaks

$ sudo dos2unix /path/to/file
$ sudo sed -i -e 's/\r$//' /path/to/file

Create new file list:

$ sed 's?^?'`pwd`'/detection_images/?; s?$?.jpg?' trainval.txt > voc.2007trainval.list