Commands using head (314)

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Merge several pdf files into a single file
merge a.pdf b.pdf and c.pdf and create ./out.pdf

Convert CSV to JSON
Replace 'csv_file.csv' with your filename.

Smart renaming
A powerfull way to rename file using sed groups. & stand for the matched expression. \1 referes to the first group between parenthesis. \2 to the second.

Find the package that installed a command

Create full backups of individual folders using find and tar-gzip
Problem: I wanted to backup user data individually. In this example, all user data is located in "/mnt/storage/profiles", and about 25 folders inside, each with a username ( /mnt/storage/profiles/mike; /mnt/storage/profiles/lucy ...) I need each individual folder backed up, not the whole "/mnt/storage/profiles". So, using find while excluding directories depth and creating two variables (tarfile=username & desdir=destination), tar will create a .tgz file for each folder, resulting in a "mike_full.tgz" and "lucy_full.tgz".

First file editor for newbies
This command should be the first file-editing command for a newbie. It clears file.txt (cat), and asks for input until EOF is entered on its own line (not written to file.txt).

Bytebeat
Never ending music, generated via a C snippet, piped to aplay. Taken from: http://canonical.org/~kragen/bytebeat/

Clear cassandra snapshots that are older than 30 days
Better than: $ nodetool clearsnapshot

One-liner to generate Self-Signed SSL Certificate+Key without any annoying prompts or CSRs
Handy if you want to quickly generate a self-signed certificate. Also can be used in your automated scripts for generating quick-use certificates.

ls -hog --> a more compact ls -l
I often deal with long file names and the 'ls -l' command leaves very little room for file names. An alternative is to use the -h -o and -g flags (or together, -hog). * The -h flag produces human-readable file size (e.g. 91K instead of 92728) * The -o suppresses the owner column * The -g suppresses the group column Since I use to alias ll='ls -l', I now do alias ll='ls -hog'


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