Bash Functions

This post contains few functions, or tips I often use, so I keep them close.

awk:

# match regexp and print
awk '/^path\.logs/{print $2}' elasticsearch.yml

cat:

cat > file.txt << "EOF"
some text
EOF

cat << EOF
Some text
    to print
EOF

envvars:

# Source envvars in the same dir as the scriptENVVARS="$(echo "${0%/*}")"/envvars
[[ -f "$ENVVARS" ]] && . "$ENVVARS" || msg fatal "envvars not found"

expect:

#!/bin/bash  # copy folder/file to remote servers (list provided from file)
# uses expect to answer yes/no and to input password
cat << EOF
USAGE:
    first argument:     file/folder (e.g. .ssh) you want to copy onto remote machine
    second argument:    file with machine list

EOF

read -p "Continue only if you have all neccassary arguments given! " w8

[[ -r $1 ]] || { echo "ERROR: nothing to copy..."; exit 3; }
[[ -r $2 ]] || { echo "ERROR: no machines list given"; exit 4; }

stty -echo
read -p "Enter password: " password; echo
stty echo

for machine in $(cat $2); do
    expect -c " 
    spawn scp -r "$1" $machine:
    
    expect { 
        "yes/no" { 
            send "yes\\r" 
                expect { 
                    "*password:" { 
                        send $password\r 
                        interact 
                    } 
                } 
        } 
        "*password:" { 
            send $password\r 
            interact 
        } 
    } 
    "
done

exit 0

find:

# find files in search dir, exept search dir and remove all which were changed more than 30 days ago
find /home/krisko/downloads -maxdepth -mindepth -ctime +30 -exec rm -rf {} \;
#NOTE: use -ok instead of -exec to be prompted

# run different action based on file types
find . '(' -type d -exec chmod o=rx {} ';' ')' -o '(' -type f -exec chmod o=r {} ';' ')'
# remove file containing text 2008
find . -type f -exec grep -q 2008 {} ';' -exec rm {} ';'

motd figlet:

while read host name; do
    figlet $host |
    ssh $name "echo "cat /home/admin/krisko/.motd" >> /home/admin/mkrissak/.bashrc; cat - >> /home/admin/krisko/.motd";
done <tmpmotd

figlet SOME_MGS | ssh <machine> "echo "cat /home/admin/krisko/.motd" >> /home/admin/mkrissak/.bashrc; cat - >> /home/admin/krisko/.motd"

msg():

# message printing with exit on ERROR/FATAL; SYNTAX: msg SEVERITY "message text"
msg() {
    SEV=$(echo -e "$1" | tr [:lower:] [:upper:])
    echo "$SEV": "$2"
    [[ "$SEV" == "ERROR" || "$SEV" == "FATAL" ]] && exit 1
}

msg error "some error message"

nohup:

nohup my_command > my.log 2>&1
echo $! > save_pid.txt

paste:

# subtract numbers in first two rowshead -2 /tmp/clusterstatt | paste -sd- - | bc

redirecting:

# redirect all (SDTOUT and STDERR)
command &>/dev/null
command &>file
command >& file

readlink:

ENVVARS="$(readlink -e "${0%/*}"/envvars)" || exit 3
. "$ENVVARS"

exec $(readlink -e $0 | sed -e 's/run.sh/XMind/')

readVal():

# read value syntax: readVal "description" "default value"
readVal(){
    read -p "Enter $[$2]: " VALUE
    [[ -n "$VALUE" ]] || VALUE="$2"
    echo $VALUE
}
[[ -n "$PORT" ]] || PORT=$(readVal "listen port" "3306")

sed:

# replace <TAG> in my.cnf with values in variables ($TAG)
for VAR in PORT SOCKET BIND_ADDRESS; do
    VALUE=$(eval echo "$"$VAR)
    sed -i "s#<$VAR>#$VALUE#" "my.cnf"
done

# apply only on matching line
sed -i '/^#node.name/s/^#//' "$INSTANCE_CONF_DIR/elasticsearch.yml"

# print only matched lines
echo -e "1\n12\n123\n1234" | sed -n '/^12[0-9]\{0,1\}$/p'

# delete Nth line
sed -i '102d' /home/SK-KOSICE/mkrissak/.ssh/known_hosts

select:

# get binaries path
[[ -n "$BINARIES" ]] || {
    info "select binaries..."
    select BINARIES in $(ls -d /pkg/*mysql/*/); do
        [[ -d "$BINARIES" ]] && break || warn "invalid folder"
    done
}

stat:

# get folder owner
PACKAGE_OWNER=$(stat -c %U folder)

tail:

# w8 for some pattern in file, then continuefifo=/tmp/tmpfifo.$$
mkfifo "${fifo}" || msg error "I'm unable to wait for LS to start"
tail -n 0 -f "$INSTANCE_LOGS_DIR/logstash.log" >${fifo} &
tailpid=$! # optional
grep -m "started" "${fifo}"
kill "${tailpid}" # optional
rm "${fifo}"

tail -fn0 "$INSTANCE_LOGS_DIR/logstash.log" | grep -m "Sending logstash logs" | xargs echo "" >> "$INSTANCE_LOGS_DIR/logstash.log" \;

w8():
# handle wait time, show some fancy progressbar (syntax w8 <time in seconds>)

w8() {
    RESET=$(tput sgr0);
    SETCOL=$(tput sgr0);
    TIME=$(echo "$1/10" | bc -l);
    PERC=10;
    HASH='##';
    for sec in {1..10}; do
        [[ "PERC" -ge 100 ]] && SETCOL=$(tput setaf 2);
        let "col=26-${#HASH}";
        printf '%s%s%s%*s%s%s\r' "$SETCOL" "$HASH" "$RESET" $col "$PERC""%";
        HASH=${HASH}"##";
        let "PERC+=10";
        sleep $TIME;
    done;
    echo -e "\n"
}

while

# w8 for status (with timeout)
while $(status &>/dev/null) && [[ "$TOUT" -gt 0 ]]; do
    echo -n "."; sleep 1; let $((TOUT-=1))
done