bash primer

Standard input/output/error

Keyboard shortcuts
^C (break), ^D (end of file), Up arrow/^P & Down arrow/^N (command recall)

Wildcard expansions and shortcuts
. and ..
*.txt (all files ending in .txt)
data0?.dat (any files starting with data0 followed by a single character and .dat)
data0[12345].dat (data01.dat through data05.dat)
data0[1-5].dat (same as above)
~ (your home directory), ~user (user's home directory)

Redirects
>, 2>, &>
>>, &>>
>&2, 2>&1

Pipes
|, 2|, -

Command terminators/seperators
;, &, &&, ||, ()

Here documents, strings
COMMAND << FILE (vs: cat FILE | COMMAND)
COMMAND <<< $VAR (vs: echo $VAR | COMMAND)
COMMAND << EOF


VAR="string"
VAR=123
VAR=$(ls)
VAR=`seq 1 10`
VAR=$((2+2))
VAR={1..10}
VAR=(string 123)
VAR[0]=string
VAR[1]=123
echo $VAR
echo ${VAR[1]}
echo $((VAR[1]))

for VAR in LIST; do COMMAND; done
for ((VAR=1; VAR < 5; VAR++)); do COMMAND; done

while EXPR; do COMMAND; done

if EXPR; then COMMAND; else COMMAND; fi
man test

if [ $VAR = 1 ]; then
if [ $VAR == "one" ]; then
if [[ $VAR == *one* ]]; then
if [[ $VAR =~ "(one|1)" ]]; then


EXAMPLES
----------------------------

for x in {1..10}; do touch data_$x.dat; done

for x in *.dat; do NUM=$(cut -d'_' -f2 <<< $x); echo $NUM; done

for x in *.dat; do NUM=$(cut -d'_' -f2 <<< $x); mv $x old_$NUM.dat; done

for x in *.dat; do mv $x $(sed -e 's/data/old/' <<< $x); done

dmesg | while read LINE; do sed -e 's/pages/potatos/' <<< $LINE; done

# print the 3rd, 7th, and 8th columns from a data table
cat table.dat | awk '{print $3, $7, $8}'

# average all the numbers in the 1st column
# first set of brackets are commands executed for every line
# second set of brackets (after END) are only executed at the end
cat table.dat | awk '{n=n+1; sum=sum+$1} END {print sum/n}'

backup.sh
runsim.sh
spawn.sh
extract.sh
tile.sh
crop.sh
include.sh
process.sh