Your favourite little helper bash scripts

[Blutkoete]

Hello!

I was wondering whether anyone wants to share his or her favourite self-programmed bash scripts that make small, but recurring tasks easier. I'm no expert on the subject, but I started to produce some scripts, so I'm curious what's out there that doesn't need to be reinvented.

My favourite at the moment is my psgrep script (I don't know whether there is a built-in command that does this):



#!/bin/bash
# psgrep: Combines ps with grep to look for specific programs directly.
ps -A | grep $1
It's simple and saved me quite some typing.

So what little helpers do you use?

Blutkoete

[matt_symes]

Hi





#!/bin/bash
# psgrep: Combines ps with grep to look for specific programs directly.
ps -A | grep $1
It's simple and saved me quite some typing.

Nice. You can also set this up as an alias and pop it into your alias file.


[matthew@localhost ~]$ alias a="ps -A | grep $1"
[matthew@localhost ~]$ a screen
1363 ? 00:00:00 gnome-screensav
1583 pts/0 00:00:00 screen
1584 ? 00:00:00 screen
[matthew@localhost ~]$

Kind regards

[Blutkoete]

Nice. You can also set this up as an alias and pop it into your alias file.


Thank you! That's much easier than my symlink-from-/usr/bin-approach :D.

[amauk]

chroot_to
If you have multiple Linux installs, this eases the process of booting into one and chrooting to another

Say you're messing around with a Gentoo install, and mess up X or the kernel - unable to boot
Boot into another distro (say Ubuntu), chroot to your Gentoo install, and you can run the Gentoo emerge package manager from the chroot

This even deals with updating grub should you install a new kernel in the chroot environment
#!/bin/bash

if [ -n "$1" ] && [ -d "$1" ]; then
CHROOT_PATH="$1"
else
exit 0
fi

mount -o bind /proc ${CHROOT_PATH}/proc
mount -o bind /dev ${CHROOT_PATH}/dev
mount -o bind /dev/pts ${CHROOT_PATH}/dev/pts
mount -o bind /sys ${CHROOT_PATH}/sys
chroot ${CHROOT_PATH} /bin/bash

CHROOT_PID=$!
wait $CHROOT_PID

echo "Unmounting chroot environment"
umount $CHROOT_PATH/sys
umount $CHROOT_PATH/dev/pts
umount $CHROOT_PATH/dev
umount $CHROOT_PATH/proc

read -p "Re-install Grub on base config? " -n 1
echo ""
if [ "$REPLY" == "y" ]; then
grub-install /dev/sda
update-grub
fi



metadata_extract
Extracts metadata from video files into a spreadsheet (resolution, aspect ratio, runtime, etc.)
See this thread for details
http://ubuntuforums.org/showthread.php?t=1300629&page=2

#!/bin/bash

TOP_DIR="/media/raid5/media/Films/"
ASPECT_RATIOS=( 1.33 1.50 1.78 1.85 2.39 )

IFS=$'\n'
MIL_SECS=1
SECS=1000
FILES=`find "$TOP_DIR" -type f | sort`

# Col headers
echo "\"Directory\",\"File Name\",\"Extension\",\"Width\",\"Height\",\"Definition\",\"Aspect Ratio\",\"Closest AR\",\"Closest AR (Human)\",\"Run Time (Accuracy is codec dependant)\""

for FILE in $FILES
do
FILENAME=`basename "$FILE" | sed 's|\(.*\)\.\(.*\)|\1|'`
FILEEXT=`basename "$FILE" | sed 's|\(.*\)\.\(.*\)|\2|'`
FILEDIR=`echo "$FILE" | sed "s|${TOP_DIR}||" | sed "s|${FILENAME}\.${FILEEXT}||" | sed 's|/$||'`

METADATA=`mplayer -vo null -identify -frames 0 "$FILE" 2>/dev/null | grep '^ID_'`

# Dimensions, Aspect Ratios, etc.
VID_WIDTH=`echo "$METADATA" | grep 'ID_VIDEO_WIDTH' | grep -o '[0-9]\+$'`
VID_HEIGHT=`echo "$METADATA" | grep 'ID_VIDEO_HEIGHT' | grep -o '[0-9]\+$'`
if [ -n "$VID_WIDTH" -o -n "$VID_HEIGHT" ]; then
VID_ASPECT_RATIO=`echo $VID_WIDTH $VID_HEIGHT | awk '{ printf("%.2f", $1/$2 ) }'`

# Hi-Def or Standard Def
if [ "$VID_WIDTH" -gt 720 ]; then
VID_DEF="HD"
else
VID_DEF="SD"
fi

# Find closest AR from 'common' film AR's
CLOSEST_AR_INDEX=""
for ((i=0; i<${#ASPECT_RATIOS[@]}; i++))
do
HOW_CLOSE=`echo "scale=2; $VID_ASPECT_RATIO - ${ASPECT_RATIOS[$i]}" | bc -l`
CLOSEST_AR_INDEX=`echo -e "${CLOSEST_AR_INDEX}\n${HOW_CLOSE}:${i}"`
done
CLOSEST_AR_INDEX=`echo "$CLOSEST_AR_INDEX" | sed 's/^-//;s/^\./0./' | sort -n | grep -o ':.*$' | sed 's/^://' | head -1`
CLOSEST_AR=${ASPECT_RATIOS[$CLOSEST_AR_INDEX]}

# Get human readable AR (x:y)
MULTIPLE=1
BREAK=0
while [ $BREAK -eq 0 ]; do
RATIO_INT=`echo "scale=2; $CLOSEST_AR * $MULTIPLE" | bc -l`
if [[ $RATIO_INT =~ ^[0-9]+\.0[0-4]$ ]]; then
RATIO_INT=`echo "$RATIO_INT" | grep -o '^[0-9]\+'`
BREAK=1
elif [[ $RATIO_INT =~ ^[0-9]+\.9[5-9]$ ]]; then
RATIO_INT=`echo "$RATIO_INT" | grep -o '^[0-9]\+'`
RATIO_INT=`expr $RATIO_INT + 1`
BREAK=1
else
MULTIPLE=`expr $MULTIPLE + 1`
fi
done
RATIO_HUMAN="${RATIO_INT}:${MULTIPLE}"
else
VID_WIDTH=0
VID_HEIGHT=0
VID_DEF="N/A"
VID_ASPECT_RATIO=0.00
CLOSEST_AR=0.00
RATIO_HUMAN="N/A"

if [ "$FILEEXT" == "mp4" ]; then
# mp4 - give benefit of doubt, and label as HD
VID_DEF="HD"
fi
fi

# Runtime calcs
RUNTIME_S=`echo "$METADATA" | grep 'ID_LENGTH' | sed 's|ID_LENGTH=\([0-9]\+\).*|\1|'`

if [ -n "$RUNTIME_S" ]; then
while [ "$RUNTIME_S" -gt 59 ]; do
RUNTIME_M=`expr $RUNTIME_S / 60`
RUNTIME_SUB=`expr $RUNTIME_M \* 60`
RUNTIME_S=`expr $RUNTIME_S - $RUNTIME_SUB`
done
while [ "$RUNTIME_M" -gt 59 ]; do
RUNTIME_H=`expr $RUNTIME_M / 60`
RUNTIME_SUB=`expr $RUNTIME_H \* 60`
RUNTIME_M=`expr $RUNTIME_M - $RUNTIME_SUB`
done
if [ "$RUNTIME_S" -lt 10 ]; then
RUNTIME_S="0${RUNTIME_S}"
RUNTIME_S=`echo "$RUNTIME_S" | sed 's|^0\+|0|;s|^0$|00|'`
fi
if [ "$RUNTIME_M" -lt 10 ]; then
RUNTIME_M="0${RUNTIME_M}"
RUNTIME_M=`echo "$RUNTIME_M" | sed 's|^0\+|0|;s|^0$|00|'`
fi
if [ "$RUNTIME_H" -lt 10 ]; then
RUNTIME_H="0${RUNTIME_H}"
RUNTIME_H=`echo "$RUNTIME_H" | sed 's|^0\+|0|;s|^0$|00|'`
fi
RUNTIME_NICE="${RUNTIME_H}:${RUNTIME_M}:${RUNTIME_S}"
else
RUNTIME_NICE="00:00:00"
fi

echo "\"${FILEDIR}\",\"${FILENAME}\",\"${FILEEXT}\",${VID_WIDTH},${VID_HEIGHT},\"${VID_DEF}\",${VID_ASPECT_RATIO},${CLOSEST_AR},\"${RATIO_HUMAN}\",\"${RUNTIME_NICE}\""
done

[matt_symes]

Hi

@amauk (http://ubuntuforums.org/member.php?u=384906)

chroot_to. I really like this. I have been chrooting the long way for far too long. Thanks for posting it. It saved me knocking up one myself. :P

Kind regards

[amauk]

Hi

@amauk (http://ubuntuforums.org/member.php?u=384906)

chroot_to. I really like this. I have been chrooting the long way for far too long. Thanks for posting it. It saved me knocking up one myself. :P

Kind regardsJust remember to make sure you change stuff to reflect your system
(like the assumption that grub is on /dev/sda)

I do tend to write stuff for my systems' setup, rather than generic stuff for any system

[amauk]

Not full scripts, but bash snippets designed for sourcing into other scripts

root_forbid & root_require
fairly self-explanatory, forbid or require root privs to run script

Example:

#!/bin/bash

. /media/scripts/include/root_require.sh

cat /etc/shadow


root_forbid

ROOT_UID=0 # Only users with $UID 0 have root privileges.
E_ROOT=68 # root exit error.

# Forbid running as root
if [ "$UID" -eq "$ROOT_UID" ]
then
echo "You are running this script as root."
echo "This has been forbidden for security reasons."
exit $E_ROOT
fi


root_require

ROOT_UID=0 # Only users with $UID 0 have root privileges.
E_NOTROOT=67 # Non-root exit error.

# Run as root, of course.
if [ "$UID" -ne "$ROOT_UID" ]
then
echo "Must be root to run this script."
exit $E_NOTROOT
fi

[DaithiF]

My favourite at the moment is my psgrep script (I don't know whether there is a built-in command that does this):

There is a command for this: pgrep :)

[Blutkoete]

Argh! pgrep is even shorter than psgrep.

I really like the root/no-root verification scripts. They come in handy.

[matt_symes]

Hi

DaithiF is bang on the money again.

pgrep is great if you just want the PID or the PID and name. It allows to do things like


kill -9 $(pgrep -x vi)

You can use the small L switch to get the process name.


matthew@matthew-laptop:~$ pgrep -l fire*
1195 firegl
3445 firefox-bin
matthew@matthew-laptop:~$

Of course there are many ways in Linux to get the same job done ;)

Kind regards

[wizard10000]

Not a script but an alias - it helps since you can't dump top to a text file. First section is sorted by memory use, second section by CPU use.


alias processes="ps -eo pid,rtprio,ni,pri,pcpu,rss,comm --sort -rss && ps -eo pid,rtprio,ni,pri,pcpu,rss,comm --sort -pcpu"

[Lars Noodén]

It allows to do things like


kill -9 $(pgrep -x vi)

Which can be done with pkill



pkill -9 -x vi

[matt_symes]

Hi


Which can be done with pkill



pkill -9 -x vi



Of course there are many ways in Linux to get the same job done

Exactly. :D

Kind regards

[Blutkoete]

Ok, I have to admit that I'm a real beginner when it's up to bash scripts (wow, amauk!), but I'll give it another shot and post something here. Maybe this time there isn't a built-in command that does the same only better :D.


#!/bin/bash
# apt-get-proxy: Executes apt-get with proxy settings (e.g. for use with apt-cache-ng). Use 0 for proxy to don't use a no proxy.
if [ "$1" = "0" ]
then
apt-get $2 $3 $4 $5 $6 $7 $8 $9
else
apt-get -o Acquire::http::Proxy="http://$1" $2 $3 $4 $5 $6 $7 $8 $9
fi


Usage: sudo apt-get-proxy <proxy-address-and-port> <normal apt-get arguments>

I use apt-cacher-ng with my netbook as the server (I take that one to the university all the time) because at home my bandwith is limited. apt-get is configured to use the netbook as a apt-cacher-ng-proxy, so I use this script if the netbook isn't running. I was always wondering whether there is something like an expression for "I want $*, only without $1" for scripting this.

I think I'll pimp up this script with amauk's root-require script.