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104 строки
2.9 KiB
Plaintext
104 строки
2.9 KiB
Plaintext
if condition; then
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commands
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elif condition; then
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commands
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else
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commands
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fi
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The newer way of doing conditios is double brackets ([[ ... ]]).
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if [[ -o interactive && -t 0 ]]; then
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mesg y
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fi
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Conditional Expression Operators:
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-b file - Tests if file is a block special file.
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-c file - Tests if file is a character special file.
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-d file - Tests if file exists and is a directory.
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-e file - Tests if file exists.
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-f file - Tests if file exists and is an ordinary file.
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-g file - Tests if file exists and has its setgid bit set.
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-k file - Tests if file exists and has its sticky bit set.
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-n string - Tests if string is nonempty.
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-o option - Tests if option is turned on.
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-p file - Tests if file exists and is a named pipe (fifo).
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-r file - Tests if file exists and is readable.
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-s file - Tests if file exists and has a size greater than zero.
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-t file descriptor - Tests if file descriptor is open and associated with a terminal device.
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-u file - Tests if file exists and has its setuid bit set.
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-w file - Tests if file exists and is writable.
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-x file - Tests if file exists and is executable.
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-z string - Tests if string is empty (length zero).
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-G file - Tests if file exists and is owned by the current group.
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-L file - Tests if file exists and is a symbolic link.
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-O file - Tests if file exists and is owned by the current user.
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-S file - Tests if file exists and is a socket.
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file1 -ef file2 - Tests if the two filenames refer to the same file.
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file1 -nt file2 - Tests if file1 is newer than file2.
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file1 -ot file2 - Tests if file1 is older than file2.
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string == pattern - Tests if the string matches the pattern.
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string != pattern - Tests if the string doesn’t match the pattern.
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string1 > string2 - Compares strings based on their ASCII values.
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string1 < string2 - Compares strings based on their ASCII values.
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string =~ regex - Tests if the string matches the regular expression (bash 3 only).
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[[ $PWD = $HOME/* ]]
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check if we are under home dir (no expansion is done at [[)
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Comparing numbers:
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[[ $val -ge 3 ]]
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(( val >= 3 ))
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case $TERM in
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(aixterm|iris-ansi*)
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bindkey ...
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;;
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(xterm|ddterm)
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bindkey ...
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;;
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esac
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[while|until] condition; do
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commands
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done
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for ((i=1;i<5;i++)); do
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a[$i]=$i
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done
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This is the same as a= ( {1..4} ).
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repeat 5; p=${p#*/}
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[break/continue] n
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break n inner loops (default is one).
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Commenting just out one command using colon (:)
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grep -q word file && : grep -q word otherfile && echo files both contain word
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here we commented out grep -q word otherfile
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colon could be used for side-effects:
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: ${VAR:?error: VAR not set}
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: ${VAR:=default value}
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Commands grouping:
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{
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cmd1
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cmd2
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} > logfile
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{ sleep 3600; make; } &
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Run commands in a subshell:
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tar cvf - . | ( cd /somwhere/else; tart xvf - )
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