Commands tagged create file (4)

  • Create arbitrary big file full of zeroes but done in a second

    If you want to create fast a very big file for testing purposes and you do not care about its content, then you can use this command to create a file of arbitrary size within less than a second. Content of file will be all zero bytes. The trick is that the content is just not written to the disk, instead the space for it is somehow reserved on operating system level and file system level. It would be filled when first accessed/written (not sure about the mechanism that lies below, but it makes the file creation super fast). Instead of '1G' as in the example, you could use other modifiers like 200K for kilobytes (1024 bytes), 500M for megabytes (1024 * 1024 bytes), 20G for Gigabytes (1024*1024*1024 bytes), 30T for Terabytes (1024^4 bytes). Also P for Penta, etc... Command tested under Linux. Show Sample Output


    3
    truncate --size 1G bigfile.txt
    ynedelchev · 2015-02-26 11:56:27 8
  • Create Bash script to change modification time of files

    Create a bash script to change the modification time for each file in 'files.txt' such that they are in the same order as in 'files.txt' File name for bash script specified by variable, 'scriptName'. It is made an executable once writing into it has been completed. Show Sample Output


    1
    scriptName="reorder_files.sh"; echo -e '#!/bin/sh\n' > "${scriptName}"; cat files.txt | while read file; do echo "touch ${file}; sleep 0.5;" >> "${scriptName}"; done; chmod +x "${scriptName}";
    programmer · 2016-04-19 11:52:00 15
  • Create a file

    Create empty file


    0
    > filename
    TIT · 2012-03-08 23:17:05 3
  • create an empty file

    When run on an existing file, alters it's creation date.


    0
    touch /path/to/file
    lolssl · 2015-09-22 16:49:22 10

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Check every URL redirect (HTTP status codes 301/302) with curl
curl -sLkIv --stderr - https://t.co/2rQjHfptZ8 -s: silences the output when piped to a different command -L: follow every redirect -k: ignores certificate errors -I: just request the headers -v: be verbose --stderr - : redirect stderr to stdout https://t.co/2rQjHfptZ8: URL to check for redirects piped to grep -i location: -i: grep target text ignoring case location: : greps every string containing "location:" piped to awk {'print $3'} prints the third column in every string piped to sed '/^$/d' removes blank lines

find all non-html files

Get AWS temporary credentials ready to export based on a MFA virtual appliance
You might want to secure your AWS operations requiring to use a MFA token. But then to use API or tools, you need to pass credentials generated with a MFA token. This commands asks you for the MFA code and retrieves these credentials using AWS Cli. To print the exports, you can use: `awk '{ print "export AWS_ACCESS_KEY_ID=\"" $1 "\"\n" "export AWS_SECRET_ACCESS_KEY=\"" $2 "\"\n" "export AWS_SESSION_TOKEN=\"" $3 "\"" }'` You must adapt the command line to include: * $MFA_IDis ARN of the virtual MFA or serial number of the physical one * TTL for the credentials

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

dont execute command just add it to history as a comment, handy if your command is not "complete" yet

Show what PID is listening on port 80 on Linux

Remove a line from a file using sed (useful for updating known SSH server keys when they change)

Output the content of your Active Directory in a CSV file

list files recursively by size

Connect-back shell using Bash built-ins

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