aXe's knowledge base

List folders by size descending recursively

find . -type d -exec du -b {} \; | sort -nr | uniq

"Too many open files"
- check current limit (only valid for executing user): "ulimit -a" or specifically "ulimit -n" ('-n' refers to "number of files")
- set limit with 'ulimit -n unlimited' or 'ulimit -n 65535' (may result in "permission denied")
- on Fedora: edit /etc/security/limits.conf

Latest changed files (one folder deep search)

find . -maxdepth 2 -type f -exec stat -c %y_%n {} \; | sort -r | less

10 latest changed files (recursively)

find . -type f -printf '%TF_%TT %p \n' | sort -r | head -n 10

Change file encoding (e. g. from UTF-8)

recode -f ascii

Use kernel prerouting to direct traffic from port 80 to 8080, e. g. for fronting tomcat

iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j DNAT --to-destination :8080

Use GNUPlot to plot vmstat output GNU Plot definition file
Repeatedly serve a file using netcat (call with wget http://localhost:12345/)

#!/bin/bash

while true
do
  { echo -ne "HTTP/1.0 200 OK\r\nContent-Length: $(wc -c <file.txt)\r\n\r\n"; cat file.txt; } | nc -l 12345
done

exit 0

Apply htdigest protection to Apache directory

-------------------------------------------------------------------------
 htaccess Protection
-------------------------------------------------------------------------
Required modules
- mod_authz_user
- mod_auth_digest
- mod_authn_file

Configuration
    <Location /path/to/protect>
       AuthType Digest
       AuthName "Protected Area"
       AuthDigestDomain /path/to/protect http://11.22.33.44/path/to/protect

       AuthDigestProvider file
       AuthUserFile /etc/apache2/conf/digest_pw
       Require valid-user
    </Location>
        

Create digest_pw file
    htdigest -c /etc/apache2/conf/digest_pw "Protected Area" username
    => will be asked for password, file created
-------------------------------------------------------------------------

Upload multiple files via FTP (which is an interactive tool) - requires curlftpfs and fuse + rsync

#!/bin/bash

SOURCE_DIR=./dist/
HOST=some.host.com
USER=username
PASS=passsword
TARGET_DIR=/target/
MOUNT_POINT=./mnt/
TMP_DIR=$(mktemp -d)

#########################################################################
## Abort if mount point does not exist
if [ ! -d ${MOUNT_POINT} ];
then
  echo "Target mount point directory does not exist, aborting."
  exit 1
fi

#########################################################################
## Mount remote file system locally
curlftpfs -o user=${USER}:${PASS} ${HOST} ${MOUNT_POINT} || exit 1

#########################################################################
## Transfer files incrementally
if [ -d "${MOUNT_POINT}/${TARGET_DIR}" ]
then
    rsync -rtuv --modify-window=1 --delete --no-perms --size-only --temp-dir=${TMP_DIR} ${SOURCE_DIR}/ ${MOUNT_POINT}/${TARGET_DIR}/
else
    echo "Target remote directory does not exist, aborting."
fi

#########################################################################
## Unmount remote file system
fusermount -u ${MOUNT_POINT}

#########################################################################
## Remove temporary directory
if [ -d "${TMP_DIR}" ];
then
    rm -rf ${TMP_DIR}
fi

exit 0

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