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Bash

Bash reminders, tips, tricks and things I've forgot.

STDERR & STDOUT

When using >> output.txt, it will only include STDOUT (Standard Output). To include errors with the output use:

  • >> output.txt 2>&1

For Loop

for i in $(ls *.*)
do;
  mv $i prefix_$i;
done

or as a one-liner: for i in $(ls *.*) do; mv $i prefix_$i; done

For Loop in Range of Numbers

for i in {1..450}
do
wget http://hostname.fqdn:8081/$i -O /dev/null
sleep 1
done

or as a one-liner: for i in {1..450}; do wget http://hostname.fqdn:8081/$i -O /dev/null; sleep 1; done

Multi-line Append

cat >> /path/to/existingFile.text<< EOF
some text line 1
some text line 2
some text line 3
EOF

Users and Groups

Create a new user

useradd [options] [user_name]

Assign/Change a password for a user

passwd [user_name]

Add a User to a Group

usermod -a -G [group_name] [user_name]