Commands by alf (5)

  • Untar a directory in a tar file over ssh

    This may be listed already but this command is useful to untar a specific directory to a different server.


    0
    cat tarfile.tar.gz | ssh server.com " cd /tmp; tar xvzf - directory/i/want"
    alf · 2011-02-11 17:10:01 1
  • Automatd ssh public key setup without ssh-copy-id

    Some servers don't have ssh-copy-id, this works in those cases. It will ask for the destination server, this can be IP, hostname, or user@hostname if different from current user. Ssh keygen will let you know if a pubkey already exists on your system and you can opt to not overwrite it.


    -2
    echo 'Host or User@Host?:'; read newserver && ssh-keygen -N "" -t rsa -f ~/.ssh/id_rsa ; ssh $newserver cat <~/.ssh/id_rsa.pub ">>" ~/.ssh/authorized_keys ; ssh $newserver
    alf · 2010-05-07 06:24:53 1
  • Show interface/ip using awk

    Interfaces like lo can be omitted from the beginning, there are probably better ways of doing this, i'm a noob at awk. Show Sample Output


    5
    ifconfig -a| awk '/^wlan|^eth|^lo/ {;a=$1;FS=":"; nextline=NR+1; next}{ if (NR==nextline) { split($2,b," ")}{ if ($2 ~ /[0-9]\./) {print a,b[1]}; FS=" "}}'
    alf · 2010-04-15 04:34:28 1
  • Update zone file Serial numbers

    Will edit *.db files in the same directory with todays date. Useful for doing a mass update to domains on a nameserver, adding spf records, etc. Looks for a string starting with 200 or 201 followed by 7 numbers, and replaces with todays date. This won't overwrite Ip's but i would still do some double checking after running this. Make sure your server's date is correct, otherwise insert your own serial number. rndc reload should usually follow this command.


    7
    sed -i 's/20[0-1][0-9]\{7\}/'`date +%Y%m%d%I`'/g' *.db
    alf · 2010-03-24 07:28:58 2
  • Use ping to test if a server is up

    Bash scrip to test if a server is up, you can use this before wget'ing a file to make sure a blank one isn't downloaded.


    -1
    if [ "$(ping -q -c1 google.com)" ];then wget -mnd -q http://www.google.com/intl/en_ALL/images/logo.gif ;fi
    alf · 2010-03-23 04:15:03 7

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Speed up builds and scripts, remove duplicate entries in $PATH. Users scripts are oftern bad: PATH=/apath:$PATH type of thing cause diplicate.

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This let you know which modules has loaded the Apache server, very useful to know if the mod_rewrite is ready to use.

Use a var with more text only if it exists
See "Parameter Expansion" in the bash manpage. They refer to this as "Use Alternate Value", but we're including the var in the at alternative.

Get IP from host
I just wanted a simple DNS request. Because host and nslookup commands are not on all systems, we use getent instead. Thanks aulem for that tip.

Grep without having it show its own process in the results
The trick here is to use the brackets [ ] around any one of the characters of the grep string. This uses the fact that [?] is a character class of one letter and will be removed when parsed by the shell. This is useful when you want to parse the output of grep or use the return value in an if-statement without having its own process causing it to erroneously return TRUE.

Search git logs (case-insensitive)
Normally, searching git log comments is case sensitive. The -i luckily applies to the --grep switch.

delete unversioned files in a checkout from svn

shell function which allows you to tag files by creating symbolic links directories in a 'tags' folder.
The tag function takes a tag name as its first argument, then a list of files which take that tag. The directory $HOME/tags/tagname will then hold symbolic links to each of the tagged files. This function was inspired by tmsu (found at https://bitbucket.org/oniony/tmsu/wiki/Home). Example: $ tag dog airedale.txt .shizturc weimeraner.pl This will create $HOME/tags/dog which contains symbolic links to airedale.txt .shizturc and weimeraner.pl

Wrap text files on the command-line for easy reading
fold wraps text at 80 characters wide, and with the -s flag, only causes wrapping to occur between words rather than through them.

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