Commands by alcik (4)

  • You can use wildcard with rpm search but you have to do 2 things: 1. use "-a" switch (means "all") with query ("-q") switch - argument is a pattern to use while searching for package names of all installed packages 2. protect wildcards, so that shell could not eat them - escape it with backslash ("\") or enclose all pattern between apostrophes ("'"): rpm -qa 'co*de' As you can see above it is possible to insert wildcards into middle of the pattern. If you want, you can add "-i" or another rpm query options, "-i" will print package information for all installed packages matching pattern. Show Sample Output


    2
    rpm -qa \*code\*
    alcik · 2009-03-11 21:16:23 1
  • This example summarize size of all pdf files in /tmp directory and its subdirectories (in bytes). Replace "/tmp" with directory path of your choice and "\*pdf" or even "-iname \*pdf" with your own pattern to match specific type of files. You can replace also parameter for du to count kilo or megabytes, but because of du rounding the sum will not be correct (especially with lot of small files and megabytes counting). In some cases you could probably use sth like this: du -cb `find /tmp -type f -iname \*pdf`|tail -n 1 But be aware that this second command CANNOT count files with spaces in their names and it will cheat you, if there are some files matching the pattern that you don't have rights to read. The first oneliner is resistant to such problems (it will not count sizes of files which you cant read but will give you correct sum of rest of them). Show Sample Output


    0
    SUM=0; for FILESIZE in `find /tmp -type f -iname \*pdf -exec du -b {} \; 2>/dev/null | cut -f1` ; do (( SUM += $FILESIZE )) ; done ; echo "sum=$SUM"
    alcik · 2009-03-05 17:16:52 3
  • It displays, last 15 yum operations (in last operation as first row order) with its dates. Change 15 to any number of operations you need to display or remove "| tac" to see it in reverse order (last operation as last row)


    0
    tail -n 15 /var/log/yum.log | tac
    alcik · 2009-03-02 08:56:04 1
  • Replace 'more' command with any command which is in your PATH. Show Sample Output


    3
    rpm -qif `which more`
    alcik · 2009-02-27 08:59:07 2

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OSX: Hear pronunciation of a word
I often use this command to learn pronunciation of unfamiliar words.

clear current line

Join lines
This command turns a multi-line file into a single line joined with <SOMETEXT>. To skip blank lines, use: $ perl -pe '(eof()||s/^\s*$//)||s/\n//g' file.txt

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"

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

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

pngcrush all .png files in the directory
Nothing too magical here, just uses pngcrush to losslessly compress all your pngs!

Simple word scramble
enlubtsqyuse $ cat /tmp/out subsequently

Display the end of a logfile as new lines are added to the end

Convert JSON to YAML
Requires installing json2yaml via npm: npm install -g json2yaml (can also pipe from stdin) Ref: https://www.npmjs.com/package/json2yaml


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