commandline session $cat test.sh #!/usr/bin/env bash # cookbook filename: checkfile # DIRPLACE=/tmp INFILE=/home/jeffrin/amazing.data OUTFILE=/home/jeffrin/more.results if [ -d “$DIRPLACE” ] then cd $DIRPLACE if [ -e “$INFILE” ] then if [ -w “$OUTFILE” ] then doscience > “$OUTFILE” else echo “can not write to $OUTFILE” fi else echo “can not read from $INFILE” fi else echo …
Author Archives: jeffrin
here-document . Bash
commandline session $cat hdoc.sh #!/bin/bash cat $1 <<EOF EOF $sh hdoc.sh bash.txt hack hacker $ $cat bash.txt hack hacker $vim hdoc.sh $ $cat hdoc.sh #!/bin/bash grep $1 <<EOF name jeffrin age 36 sex male EOF $sh hdoc.sh 3 age 36 $
nohup . no hangup
commandline session $cat loop.c main() { for (;;); } $./a.out ^C $nohup ./a.out nohup: ignoring input and appending output to `nohup.out’ ^C $cat nohup.out $ls nohup.out nohup.out $
Bash . Running Several Commands All at Once
commandline session $ls src war $cd & ls & [1] 2587 [2] 2588 $src war [1]- Done cd [2]+ Done ls –color=auto $pwd /home/jeffrin/beautiful-work $ $cd & ls & cd & [1] 2590 [2] 2591 [3] 2592 $src war [1] Done cd [2]- Done ls –color=auto [3]+ Done cd $pwd /home/jeffrin/beautiful-work $cd .. & pwd …
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input redirection indicated by < character
commandline session $cat bash.txt hack hacker $cat < bash.txt hack hacker $wc < bash.txt 2 2 12 $wc -l yab.txt $cat yab.txt hello $wc < yab.txt 1 1 6 $
Basic tinkering with “set” command and “noclobber” related
commandline session [bash light=”true”] $echo improve > clean.txt $cat clean.txt improve $set -o noclobber $echo new > clean.txt bash: clean.txt: cannot overwrite existing file $echo new >> clean.txt $cat clean.txt improve new $echo again >| clean.txt $cat clean.txt again $set +o noclobber $echo improve > clean.txt $cat clean.txt improve $ [/bash]
Bash . set -o noclobber . environment manipulation
commandline session $set -o noclobber $ls a.out a.out $ls > a.out bash: a.out: cannot overwrite existing file $ $set +o noclobber $ $ls > a.out $rm a.out $
tput Query Terminfo Database
commandline session $tput cup 3 4 $tput cup 4 3 $tput cols 140 $tput lines 39 $tput setb 4 $tput setb ` > ^C > ^C $^C $tput setb 0 $ $tput setb 1 $ $
Grouping Output from several commands
commandline session $cd autotest/ $ls autotest cyclictest ${ ls ; pwd ; cd cyclictest ; ls ; pwd } > /tmp/all.out > ^C ${ ls ; pwd ; cd cyclictest ; ls ; pwd ; } > /tmp/all.out $cat /tmp/all.out autotest cyclictest /home/jeffrin/autotest client.DEBUG /home/jeffrin/autotest/cyclictest $
Errors and Exceptions
commandline session $gcc error.c $cat error.c #include main() { int a=0; int b=10; printf(“Hello Alln”); printf(“%d”,b/a); } $./a.out > outputa Floating point exception $cat outputa $ $./a.out 2> outputa Hello All Floating point exception $./a.out > outputa Floating point exception $./a.out 2> outputb Hello All Floating point exception $./a.out &> outputc Floating point exception $cat …