Some useful command lines for Linux systems

By admin, February 20, 2018

Once in a while, as programmers or system administrators, we face the need of issuing commands we might not remember by heart. So I came out with the following list (to be constantly updated) related to this topic.

I have been using mostly the CentOS and Ubuntu distros, so most of them may be applied in most Linux flavours.

Finding files and content

Find a file, by filename recursively:
find . -name “composer*”
Find a file, by filename, recursively, case insensitive
find . -print | grep -i composer.phar
To search inside symbolic links:
find -L . -name “composer*”
For find only FILES, mention -type f
find -L . -type f -name “composer*”
For find with REGEX
find -L . -type f -iname “composer.
Find file containing a text (pattern) -r = recursive, -n number of line -w stand for all word -l could be lower case

My prefered

grep -rnw ‘/path/to/somewhere/’ -e ‘pattern’

grep -rnw . –color –exclude-dir={custom,vendor} -e ‘$_GET’

Showing only folders when needed

grep -r [regex to find] [path to search] | awk -F: ‘{print $1}’ | uniq

Replacing recursively a text for another recursively

find /path/to/files -type f -exec sed -i ‘s/oldstring/new string/g’ {} \;

Check directory and files size in Linux

View directories
du -h dirunix/

View directories and files
du -ah dirunix/

View a summary
du -sh dirunix/

Empty big huge great files content in Linux
#du -sh access.log
1.1G
#> access.log
or
#true > access.log
or
#cat /dev/null > access.log
or
#cp /dev/null access.log
or
#echo -n “” > access.log # -n stands for null
or
#truncate -s 0 access.log

#du -sh access.log
0

ZIP File operations

Include just cetain types of files or directories
zip -r foo website_folder -i ‘*.php’ ‘*.html’ ‘*.js’ ‘*.css’

Exclude files or dir: -x e.g.
Directory: zip -r archivename.zip directorytozip -x “*.git*”
File: zip -r archive.zip directory -x “*.jpg”