Running Bash As Another User

[root@cicd-02 ~]# sudo -u jenkins /bin/bash
bash-4.2$ whoami
jenkins

Find In Files Recursively

Its helpful to be able to search for a string recursively in a directory. Here is the basic way:

grep -rnw '/path/to/somewhere/' -e "pattern"

-r or -R is recursive, -n is line number and -w stands match the whole word. -l (lower-case L) can be added to just give the file name of matching files.

Along with these, --exclude or --include parameter could be used for efficient searching. Something like below:

grep --include=\*.{c,h} -rnw '/path/to/somewhere/' -e "pattern"

This will only search through the files which have .c or .h extensions. Similarly a sample use of --exclude:

grep --exclude=*.o -rnw '/path/to/somewhere/' -e "pattern"

Above will exclude searching all the files ending with .o extension. Just like exclude file it's possible to exclude/include directories through --exclude-dir and --include-dir parameter; for example, the following shows how to integrate --exclude-dir:

grep --exclude-dir={dir1,dir2,*.dst} -rnw '/path/to/somewhere/' -e "pattern"

Replace Recursively

find /home/www -type f -print0 | xargs -0 sed -i 's/subdomainA.example.com/subdomainB.example.com/g'

Truncating Git History

Look, sometimes you want to be a revisionist, and the only way to get rid of a pesky diff that is taking a lot of commit time is to truncate the commit log. So in the rare occasion you need to do it here is how.

Create a Truncate Script

	#!/bin/bash
	git checkout --orphan temp $1
	git commit -m "First commit"
	git rebase --onto temp $1 master
	git branch -D temp

view raw git-truncate.sh hosted with ❤ by GitHub

Use the Commit Sha to Truncate To

source ~/data/bin/git-truncate a71f4386f9d5e3b707067e66fd5f76a1cc06c11c

Force the Push to Origin

git push origin master --force