Conditionally dry run a command block with BASH heredoc
I wanted to have something as simple as that in my script:
set_dryrun()
{
BEGIN='cat << EOF'
END='EOF'
}
[ "$1" == "-dryrun" ] && set_dryrun
${BEGIN}
ls -l
${END}
So that if I run it with the -dryrun parameter, commands between ${BEGIN} and ${END} would be just printed, but not executed.
Everything goes well if I run without the -dryrun flag:
$ ./dryrun_opt
-rwxrwxr-x 1 arantesj arantesj 160 jan 25 17:15 dryrun_opt
With -dryrun, though, I see:
$ ./dryrun_opt -dryrun
cat: '<<': No such file or directory
cat: EOF: No such file or directory
-rwxrwxr-x 1 arantesj arantesj 160 jan 25 17:16 dryrun_opt
./dryrun_opt: line 14: EOF: command not found
Well... I am not replacing (expanding?) my heredoc correctly, I know, but how should I, if possible?
Thanks in advance.
bash bash-scripting debug
asked Jan 25 at 16:20
j4xj4x
1175
add a comment |
I wanted to have something as simple as that in my script:
set_dryrun()
{
BEGIN='cat << EOF'
END='EOF'
}
[ "$1" == "-dryrun" ] && set_dryrun
${BEGIN}
ls -l
${END}
So that if I run it with the -dryrun parameter, commands between ${BEGIN} and ${END} would be just printed, but not executed.
Everything goes well if I run without the -dryrun flag:
$ ./dryrun_opt
-rwxrwxr-x 1 arantesj arantesj 160 jan 25 17:15 dryrun_opt
With -dryrun, though, I see:
$ ./dryrun_opt -dryrun
cat: '<<': No such file or directory
cat: EOF: No such file or directory
-rwxrwxr-x 1 arantesj arantesj 160 jan 25 17:16 dryrun_opt
./dryrun_opt: line 14: EOF: command not found
Well... I am not replacing (expanding?) my heredoc correctly, I know, but how should I, if possible?
Thanks in advance.
bash bash-scripting debug
asked Jan 25 at 16:20
j4xj4x
1175
add a comment |
I wanted to have something as simple as that in my script:
set_dryrun()
{
BEGIN='cat << EOF'
END='EOF'
}
[ "$1" == "-dryrun" ] && set_dryrun
${BEGIN}
ls -l
${END}
So that if I run it with the -dryrun parameter, commands between ${BEGIN} and ${END} would be just printed, but not executed.
Everything goes well if I run without the -dryrun flag:
$ ./dryrun_opt
-rwxrwxr-x 1 arantesj arantesj 160 jan 25 17:15 dryrun_opt
With -dryrun, though, I see:
$ ./dryrun_opt -dryrun
cat: '<<': No such file or directory
cat: EOF: No such file or directory
-rwxrwxr-x 1 arantesj arantesj 160 jan 25 17:16 dryrun_opt
./dryrun_opt: line 14: EOF: command not found
Well... I am not replacing (expanding?) my heredoc correctly, I know, but how should I, if possible?
Thanks in advance.
bash bash-scripting debug
asked Jan 25 at 16:20
j4xj4x
1175
I wanted to have something as simple as that in my script:
set_dryrun()
{
BEGIN='cat << EOF'
END='EOF'
}
[ "$1" == "-dryrun" ] && set_dryrun
${BEGIN}
ls -l
${END}
So that if I run it with the -dryrun parameter, commands between ${BEGIN} and ${END} would be just printed, but not executed.
Everything goes well if I run without the -dryrun flag:
$ ./dryrun_opt
-rwxrwxr-x 1 arantesj arantesj 160 jan 25 17:15 dryrun_opt
With -dryrun, though, I see:
$ ./dryrun_opt -dryrun
cat: '<<': No such file or directory
cat: EOF: No such file or directory
-rwxrwxr-x 1 arantesj arantesj 160 jan 25 17:16 dryrun_opt
./dryrun_opt: line 14: EOF: command not found
Well... I am not replacing (expanding?) my heredoc correctly, I know, but how should I, if possible?
Thanks in advance.
bash bash-scripting debug
bash bash-scripting debug
asked Jan 25 at 16:20
j4xj4x
1175
asked Jan 25 at 16:20
j4xj4x
1175
asked Jan 25 at 16:20
j4xj4x
1175
asked Jan 25 at 16:20
j4xj4x
1175
asked Jan 25 at 16:20
j4xj4x
1175
1175
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
This works for me:
set_dryrun()
{
BEGIN='cat << EOF'
END='EOF'
}
[ "$1" == "-dryrun" ] && set_dryrun
eval "${BEGIN}
ls -l
${END}"
However, I suspect that this whole approach will break at some point, when the heredoc becomes more complex than 'ls -l'. If there were quoting or escaping going on inside that, it would need to be done carefully or an approach this simple is likely to break.
Borrowing from the wisdom of this Stack Overflow thread, you might find this approach interesting to consider:
if [ "$1" == "-dryrun" ]
then
CMD="cat"
else
CMD="bash" # your preferred shell here
fi
WORK="$(cat <<'EOF'
# abc'asdf"
# $(dont-execute-this)
# foo"bar"''
ls -l
echo "$PATH"
echo "$PATH"
EOF
)"
$CMD <<< "$WORK"
answered Jan 25 at 17:46
Jim L.Jim L.
44117
Great! It worked fine for my current needs, but I will keep in mind (and text) your advice. Thank you @Jim-L.
– j4x
Jan 28 at 6:42
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
This works for me:
set_dryrun()
{
BEGIN='cat << EOF'
END='EOF'
}
[ "$1" == "-dryrun" ] && set_dryrun
eval "${BEGIN}
ls -l
${END}"
However, I suspect that this whole approach will break at some point, when the heredoc becomes more complex than 'ls -l'. If there were quoting or escaping going on inside that, it would need to be done carefully or an approach this simple is likely to break.
Borrowing from the wisdom of this Stack Overflow thread, you might find this approach interesting to consider:
if [ "$1" == "-dryrun" ]
then
CMD="cat"
else
CMD="bash" # your preferred shell here
fi
WORK="$(cat <<'EOF'
# abc'asdf"
# $(dont-execute-this)
# foo"bar"''
ls -l
echo "$PATH"
echo "$PATH"
EOF
)"
$CMD <<< "$WORK"
answered Jan 25 at 17:46
Jim L.Jim L.
44117
Great! It worked fine for my current needs, but I will keep in mind (and text) your advice. Thank you @Jim-L.
– j4x
Jan 28 at 6:42
add a comment |
This works for me:
set_dryrun()
{
BEGIN='cat << EOF'
END='EOF'
}
[ "$1" == "-dryrun" ] && set_dryrun
eval "${BEGIN}
ls -l
${END}"
However, I suspect that this whole approach will break at some point, when the heredoc becomes more complex than 'ls -l'. If there were quoting or escaping going on inside that, it would need to be done carefully or an approach this simple is likely to break.
Borrowing from the wisdom of this Stack Overflow thread, you might find this approach interesting to consider:
if [ "$1" == "-dryrun" ]
then
CMD="cat"
else
CMD="bash" # your preferred shell here
fi
WORK="$(cat <<'EOF'
# abc'asdf"
# $(dont-execute-this)
# foo"bar"''
ls -l
echo "$PATH"
echo "$PATH"
EOF
)"
$CMD <<< "$WORK"
answered Jan 25 at 17:46
Jim L.Jim L.
44117
Great! It worked fine for my current needs, but I will keep in mind (and text) your advice. Thank you @Jim-L.
– j4x
Jan 28 at 6:42
add a comment |
This works for me:
set_dryrun()
{
BEGIN='cat << EOF'
END='EOF'
}
[ "$1" == "-dryrun" ] && set_dryrun
eval "${BEGIN}
ls -l
${END}"
However, I suspect that this whole approach will break at some point, when the heredoc becomes more complex than 'ls -l'. If there were quoting or escaping going on inside that, it would need to be done carefully or an approach this simple is likely to break.
Borrowing from the wisdom of this Stack Overflow thread, you might find this approach interesting to consider:
if [ "$1" == "-dryrun" ]
then
CMD="cat"
else
CMD="bash" # your preferred shell here
fi
WORK="$(cat <<'EOF'
# abc'asdf"
# $(dont-execute-this)
# foo"bar"''
ls -l
echo "$PATH"
echo "$PATH"
EOF
)"
$CMD <<< "$WORK"
answered Jan 25 at 17:46
Jim L.Jim L.
44117
This works for me:
set_dryrun()
{
BEGIN='cat << EOF'
END='EOF'
}
[ "$1" == "-dryrun" ] && set_dryrun
eval "${BEGIN}
ls -l
${END}"
However, I suspect that this whole approach will break at some point, when the heredoc becomes more complex than 'ls -l'. If there were quoting or escaping going on inside that, it would need to be done carefully or an approach this simple is likely to break.
Borrowing from the wisdom of this Stack Overflow thread, you might find this approach interesting to consider:
if [ "$1" == "-dryrun" ]
then
CMD="cat"
else
CMD="bash" # your preferred shell here
fi
WORK="$(cat <<'EOF'
# abc'asdf"
# $(dont-execute-this)
# foo"bar"''
ls -l
echo "$PATH"
echo "$PATH"
EOF
)"
$CMD <<< "$WORK"
answered Jan 25 at 17:46
Jim L.Jim L.
44117
edited Jan 25 at 18:20
answered Jan 25 at 17:46
Jim L.Jim L.
44117
answered Jan 25 at 17:46
Jim L.Jim L.
44117
answered Jan 25 at 17:46
Jim L.Jim L.
44117
44117
Great! It worked fine for my current needs, but I will keep in mind (and text) your advice. Thank you @Jim-L.
– j4x
Jan 28 at 6:42
add a comment |
Great! It worked fine for my current needs, but I will keep in mind (and text) your advice. Thank you @Jim-L.
– j4x
Jan 28 at 6:42
Great! It worked fine for my current needs, but I will keep in mind (and text) your advice. Thank you @Jim-L.
– j4x
Jan 28 at 6:42
Great! It worked fine for my current needs, but I will keep in mind (and text) your advice. Thank you @Jim-L.
– j4x
Jan 28 at 6:42
add a comment |
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