Commonly used action statements in shell script files

1. Clear the contents of the file

Cat/dev/null >>/var/log/messages

2. The script to determine whether the user is the root user

Root_uid = 0 # $UID is 0 o'clock, the user has root user rights

If ["$UID"-ne "$ROOT _uid"]

Then

echo "This user isn't root"

Exit 1

Fi

3. Multiple statement conditions run

Statement 1 && Statement 2 # statement 1 correct, run statement 2 again

Statement 1 | | Statement 2 # statement 1 failed with statement 2 executed

Statement 1 | | {

Statement 2

Statement 3 # When multiple statements are in a block, enclose them in {}

}

Commonly used action statements in shell script files